Imogen James
Live reporter

The first round of Transport for London (TfL) strikes kicked in at midday, and is due to last until 11:59 BST on Wednesday, as drivers of the Rail, Maritime and Transport union start a series of 24-hour walkouts.

As the Tube strikes came into effect, delays and closures greeted commuters and visitors. While some lines were quiet, others were packed, with passengers queuing on platforms and unable to board trains.

Customers were advised to end their Tube journeys by 20:00 BST today, as there will be no services this evening.

On Wednesday, there's no services before 07:30, and it's expected to be busy when they do begin.

No service is expected on the Piccadilly and Circle lines during this strike - though the Piccadilly line was only part suspended on Monday. The Metropolitan line will not run between Baker Street and Aldgate, while the Central line is suspended between White City and Liverpool Street.

The Elizabeth line, London Overground, trams and buses continue to run but are expected to be busier than usual.

You can find out the latest on the TfL website, external, which helps you plan ahead and see where the disruption is. Safe travels, we're pausing our coverage and will be back here in the morning.

• TfL Tube strikes: What you need to know

There's mixed reaction to the strikes from people visiting London.

Anna, who is visiting from Toronto with her husband, tells BBC Radio London they've been spending the day looking at museums before they try to "figure out a way to get back to where we started from".

She says they're going to have a "wonderful" time and if they don't have to be anywhere, "it's not a problem".

Greg, from Plymouth, says the strikes are "slightly inconvenient".

He says they didn't know about the strikes until yesterday, but that his party is leaving the capital this evening via Paddington. They will either walk or try and get a bus to the train station.

Half of Transport for London (TfL) passenger services were not in operation as of 14:00 BST today, the transport network says.

It says taps were 13% down for people using their Oyster travel card compared to expected levels, and there was stronger service than expected on the Jubilee, Bakerloo, Victoria and Metropolitan lines.

More people opted for cycle hires today, it says, with demand up by 14%.

Demand for vehicles was stable, with pockets of congestion, it says, adding that passengers are advised of the late start to Tube services tomorrow, which won't start until 07:30.

Jess Warren
BBC London

Bar owner Simon Williams calls the strike action a "nail in the coffin for businesses like ours".

Williams, the chief executive of Zodiac Bar in Camden, says: "We will inevitably lose revenue because of this.

"Many of our customers use the London Underground to visit our venue, and we also partly rely on commuter footfall, which will be nonexistent on strike nights as we have experienced previously."

Ayshea Buksh
BBC London reporter

It appears some Tube trains are running this rush hour, but just not as frequently as London commuters and visitors are used to.

This was the noticeboard at Euston station today. Platforms are very full as people wait for the next train during the rush hour commute.

When the trains do arrive, they are very, very full and I've been unable to board a train I've been waiting for, so now I'll walk!

Image source, Reuters

Transport for London (TfL) are advising travellers to complete their journeys by 20:00 this evening as Tube services are finishing early due to the strikes.

The first of six scheduled RMT Tube strikes began at 12:00 BST today.

The strike is set to run for 24 hours, ending at 11:59 on Wednesday, with significant disruption expected on many networks.

The Tube services that are running on Wednesday are expected to start later than usual with no service before 07:30.

Passengers are being reminded to check their journeys ahead of travelling - with a second strike expected on Thursday.

James W Kelly
At King's Cross station

At King's Cross things are relatively calm and quiet but some would-be Piccadilly line passengers are being caught out by the closure.

One of those was South, who is trying to meet his sister at Hyde Park Corner.

He says: "Now I have no idea where I'm going. I'm stuck here oblivious as to how I can get back to Hyde Park Corner.

"TfL could have done a better job keeping people informed."

Image source, EPA/Shutterstock

Transport for London (TfL) has apologised for the disruption caused so far by the Tube strikes called by the Rail, Maritime and Transport (RMT) union, and says it is "very confident" a solution will, eventually, be found.

Nick Dent, TfL's director of customer operations for the London Underground, tells BBC Radio London: "I understand the frustration and I do apologise sincerely for that."

He says it is "not too late" for the RMT to call off the second wave of strikes scheduled for later in the week, but says TfL are "planning on the basis that it is going ahead".

On the demands of the RMT, which says plans to introduce a voluntary compressed four-day working week could lead to fatigue and impact safety, Dent says TfL's proposals have followed "very extensive engagement" with unions.

"We've worked very hard to avoid getting into this situation this week. We've explained to the RMT that we think most of their concerns that they're raising can and will be addressed," he says.

He adds that he is "very confident" that a solution can be found with the RMT, and urges them to suspend further strikes and "continue the talks".

Tom Edwards
Transport Correspondent, BBC London

It's really difficult for commuters to know if there's a service on the line they want to travel on during rush hour this evening.

I've just been in Covent Garden, where one minute the station shutters were completely closed, then the next minute there was a train in 25 minutes.

If you look at the board, the Hammersmith and City and Picadilly lines are part suspended, while the Bakerloo, District and Victoria lines all have severe delays.

It's very difficult to get around and there is a lot of disruption.

Commuters should consider using the Elizabeth line, the overground and buses where possible.

It's been over five hours since the RMT Tube strike began with many lines across London still heavily impacted as commuters make their way home during rush hour.

Transport for London (TfL) has listed the Circle line as fully suspended and the Piccadilly as part suspended - these are the two lines where no service was expected during the strike.

Other affected lines are the Metropolitan, which will not run between Baker Street and Aldgate, while the Central line is suspended between White City and Liverpool Street.

Severe delays continue on the Bakerloo and Victoria lines, as well as on District, Jubilee and Waterloo & City lines. There are also minor delays reported on the Northern line.

The Windrush line has minor delays as a result of a signal failure rather than strike action.

Image source, BBC London via TfL Open Data

James W Kelly
At Finsbury Park station

At Finsbury Park station the buses are becoming busy with the end of the school day and workers beginning their evening commute.

While buses are often busy at the north London transport hub, it was noticeable how many disembarked at Manor House station - the closed next stop on the Piccadilly line.

There has been relative calm so far today in my experience, but we will see whether that changes during this evening's rush hour and into tomorrow morning.

Image source, EPA/Shutterstock

Drone pictures have captured the depot at the end of the Piccadilly line filled with trains as strike action approaches its sixth hour.

The Circle and Piccadilly line were expected to be the most impacted, with the Circle line completely suspended since the strike began at midday.

On the Piccadilly, TfL now says the service has been suspended in both directions on the entire line except from Acton Town to Heathrow, which is operating a reduced frequency service.

Image source, EPA/Shutterstock

James W Kelly
On the Victoria line

On the Victoria line heading north and carriages certainly aren’t any busier than normal for a weekday afternoon.

People I’ve spoken to throughout the day say many of their friends and colleagues are working from home to avoid potential disruption.

The real test comes over the next few hours as those who commuted into work this evening without issue begin their journey home.

Tom Edwards
Transport Correspondent, BBC London

Unlike during the Tube strikes in September last year, more trains are running with the entire network not being shut down.

This is because members of the Aslef union are not joining in the walkout having agreed the deal.

An Aslef spokesperson previously told BBC London they were "surprised that the RMT has decided to take this action.

"The voluntary four-day week gives Tube drivers an extra 35 days off every year with rosters based on a 34-hour week in return for some fairly minor changes to working conditions and moving to electronic, rather than paper based systems for booking on for duty.

"And as its voluntary, anyone who wants to keep working a five-day week will be able too. Most people will regard that as a pretty good deal.

"It will be the first strike in the history of the trade union movement designed to stop people having a shorter working week and more time off.”

Image source, PA Media

There is "absolute unanimity" among members of the RMT union that action is needed to fight the proposals put forward, says the RMT's Jared Wood at a picket alongside striking workers.

The union is taking action over plans to introduce a voluntary compressed four-day working week, which it says could lead to fatigue and impact safety.

Wood says the strike is not just about a four-day week, but that there are other issues were involved, such as the length of shifts and changes to annual leave.

"TfL need to come forward with changes to their proposals for this dispute to be resolved," he says, adding that there was now “a lot of bad feeling” between the drivers and London Underground.

“There is absolute unanimity among our members that we have to fight these proposals."

TfL has said the proposed changes "allows us to offer train operators an additional day off" and "would be voluntary".

James W Kelly
Outside King's Cross station

George, another stallholder outside King's Cross station, says today has been a "particularly quiet" Tuesday due to the strikes.

He says his customers are made up of commuters and tourists, so he's worried about the likely impact over the week as strikes continue.

Despite the potential impact on business, his message to striking RMT drivers is to "keep up the fight".

James W Kelly
Outside King's Cross station

One stall worker at the Real Food Market, outside King's Cross station, says despite the lovely weather there's been next to no footfall due to the strikes.

"It's really heavily impacted sales, especially today," says Mimi, on the Borough Cheese Company stall.

"There's been like no people walking through, so no customers," she says, adding that she also struggled to get into work today.

"Usually when it sunny more people are out... more people want to spend their money, all good, but even though the sun's out today no ones here because the Tubes aren't running," she adds

Barry Caffrey
At South Kensington station

Here at South Kensington station I've been speaking to those who've been impacted by the strikes.

Earlier, Elena told me she'd been caught out by them while trying to fly back home.

"I'm trying to get to Victoria station to catch my flight back to Denmark, from Gatwick," she told me.

"I was about to take a walk, but it's going to take like 40 minutes," she added.

"So yeah, I might be missing my flight."

The shutters are coming down on some stations along the Piccadilly line with passengers turned away as the full effects of the strike begin to show.

In its latest update, TfL says the Piccadilly line is shut westbound between Cockfosters and Acton Town, with reduced service further west.

It adds that the eastbound service between those stations two is still running - for now - however our reporter at Covent Garden says there is no service at the station.

The TfL app is reporting a few eastbound trains in service.

Two hours since the RMT Tube strike went into effect, there is disruption across many lines throughout London.

Transport for London (TfL) lists the Circle line as fully suspended and the Piccadilly as part suspended - these are the two lines where no service is expected when the strikes are in place.

Other affected lines are the Metropolitan, which will not run between Baker Street and Aldgate, while the Central line is suspended between White City and Liverpool Street.

However, as TfL previously warned, there is disruption elsewhere on the network, with the Bakerloo, District, Jubilee all reporting severe delays - with the Northern and Victoria linesreporting minor delays.

The Windrush line has minor delays as a result of a signal failure rather than strike action.