Local councillor Chris Vinson says "several hundred masked men" have been blocking local roads.

“There are stacks of people who are stuck in their cars or in their workplaces as a result," says Vinson, who is leader of the Conservative group at Dover District Council.

He says the protest appears to be “illegal migration-related”, although demonstrators did not appear to have placards or banners.

“I’m not aware that there’s been any violence, although clearly, having the path of your vehicle blocked by men wearing black paramilitary gear and balaclavas is extremely intimidating," he adds, "especially when it’s not clear why they’re there and the police weren’t aware."

Vinson describes how some port workers on night shifts were "being prevented from leaving for fears for their safety", while some women in cars were "feeling intimidated".

Traffic is now able to enter and leave the Port of Dover via the A2 Jubilee Way, the port says.

A post on the port's X account tells customers if they cannot make their booking then Irish Ferries, DFDS and P&O Ferries will allow them on their next available sailing.

Remco van Schellen arrived in Dover from the Netherlands at about 08:00 BST.

He says that when he wanted to leave the ferry terminal with his car "we couldn't go any further".

"There were people blocking the roads, the roundabout, just outside of the ferry terminal in Dover," he tells the BBC.

"There were people in black clothing, their faces masked, so we couldn't see who they were."

He adds: "It was my welcome party here."

Image source, Remco van Schellen

Simon Jones
Reporting from Dover

There are lots of police here, they are marching protesters towards Dover railway station.

The demonstrators have been chanting: "Stop the boats."

Protesters told me they don’t want to talk to the media, though one said: "Send them back" and another said: "Stop the boats."

The Port of Calais in France is not currently being affected by the protest in Dover.

A spokesperson for the port tells the BBC operators are continuing to load cargo, although ships are departing with slight delays.

The port is monitoring the situation, the spokesperson adds.

Image source, PA Media

The Port of Dover is the UK’s busiest international ferry port with over 15,000 passenger vehicles using it each day in the summer.

More than 10,000 freight vehicles also pass through the port each day and the site handles £144bn of trade each year.

Around 33% of UK trade with the European Union moves across the Channel from the port.

The site is also home to 25 different cruise lines and thousands of guests each year.

National Highways says the A20 east between A256 (York Street) and A2 (Jubilee Way) remains closed, with around one mile (1.6km) of congestion and 25-minute delays on approach.

In its latest update on X, it says the westbound route is "mostly clear of traffic, but remains blocked from Limekiln roundabout".

Image source, UK Parliament

Dover and Deal MP Mike Tapp, pictured above, tells the BBC the incident is causing "absolutely awful disruption" for residents.

"My understanding is a number of individuals have travelled to the area, wearing black, wearing balaclavas, and have blocked a number of roads leading into the port area," he says.

Paul King, Reform UK councillor for Dover West, says he has been told the demonstration is a "stop the boats protest".

Tapp adds on Facebook: "I am fed up with idiots coming to Dover to cause disruption.

"I bet if you asked any one of those 'protesters' they wouldn't know small boat crossing are down by 40% and we are working hard to fix the mess."

Kent Police has not yet commented on who is behind the protest.

P&O Ferries says access to the port "has been partially restored and traffic is currently able to access the port via the M2/A2, access remains restricted from the M20/A20".

It adds services are operating "with some delay" amid the disruption, but is promising to get passengers onto the next available sailing when they reach check-in.

Meanwhile, ferry operator DFDS says it is aware of the "current traffic disruption" and will accommodate passengers on the next departure once they arrive.

There is major disruption at the Port of Dover due to a large group of masked men holding a demonstration.

National Highways says protesters are "blocking all traffic entering the port".

Traffic is stopped in both directions on the A20 between A256 York Street & A2 Jubilee Way, it says, with around three miles (4.8km) of congestion and 30 minute delays on approach.

Kent Police says it is aware of a protest "currently taking place" at the ferry terminal and is "engaging with protesters".

This is a breaking news story – we’ll bring you updates here.