HS2 could cost up to £102.7bn and trains will be slower than first planned

HS2 could now cost up to £102.7bn, the transport secretary has announced,but vowed the government will deliver the project "to completion".

Trains will not start running until between 2036 and 2039, up to six years later than the most recent official target of 2033, Heidi Alexander told the House of Commons.

To save money, the trains' top speed - originally planned to be 360km/h (224mph) - will be reduced to 320km/h.

The new cost range,delayed start and lower train speed are being announced as a "reset" of the delayed, over-budget and vastly scaled-back project is carried out.

Heidi Alexander has published the Lovegrove report into the project, which she said details the "litany of failure" Labour inherited from the previous government.

"Instead of signalling the country's ambition, HS2 became a signal of the country's decline," she told MPs.

Alexander said the rail project was now expected to cost between £87.7bn and £102.7bn in 2025 prices.

"If it seems like an obscene increase in time and costs, it is because it is," she said. "If it seems like I'm angry, it is because I am."

In 2013, the project was forecast to cost £50.1bn in 2011 prices, which is the equivalent of about £75bn in today's money, when accounting for inflation.

However, that forecast was made when the line was still due to go to Manchester and Leeds. The current project is set to run from London to Birmingham.

Alexander said the government was committed to delivering the project despite the cost increase.

Two-thirds of the increase in cost is due to an underestimate of costs by the previous government, inefficient delivery, and to works being missed from the scope of the original plan, according to the government. One third of the increase is due to inflation, Alexander said.

The new, lower speed for HS2 trains is in line with high-speed services in Europe and Japan, and the government says it could save up to £2.5bn and allow the project to be delivered a year earlier.

The updated timeline for the start of services is for trains between Old Oak Common in west London and Birmingham Curzon Street.

The full service from London Euston to Curzon Street and a connection to the West Coast Main Line is not expected to run until between 2040 and 2043.

"We will get the job done but we will also take every opportunity to save time and money in the process, getting a grip on delivery, controlling costs, and stripping out the complexity that's plagued the project in the past," she said.