This article is more than 1 year old

This article is more than 1 year old

The planned HS2 high-speed railway line could surpass its budget by up to £30bn, the chairman of the project has reportedly warned.

Allan Cook has written to Bernadette Kelly, the permanent secretary at the Department for Transport, to warn that the high-speed line from London cannot be finished within the official £56bn budget, the Financial Times reported.

The paper reported that according to Cook’s preliminary findings, the infrastructure project’s final cost could spiral to between £70bn and £85bn.

A source close to the project told the newspaper the costs had increased because of a “combination of poor ground conditions found during the surveying work, the costs of engineering a railway to a very high specification, and the further additional costs of it being designed to run at even higher speeds than other comparable rail projects”.

HS2, scheduled to open in sections between the end of 2026 and 2033, will stretch from Euston station in London to Birmingham in its first phase and subsequently to Leeds and Manchester.

Cook was brought in to take control of the project in December following the departure of Sir Terry Morgan, who also quit as chair of Crossrail.

Last month the transport secretary, Chris Grayling, revealed Cook had been reassessing the costs and the expected time overruns and considering whether cutbacks could be made.

“I’m really waiting for Allan [Cook] to come back to me to say this is how we’re going to take the project forward,” he told New Civil Engineer magazine.

Boris Johnson, the frontrunner to succeed Theresa May as prime minister next week, has appointed Douglas Oakervee, a former HS2 chairman, to undertake a review of the project’s scope and costs.

A spokesman for HS2 said the group did not comment on leaks.

“We have previously noted that our chair, as you would expect, continues to scrutinise the programme, and regularly reports back to the department,” he said.

“We are determined to deliver a railway that rebalances the economy, creates jobs, boosts economic growth and is value for money for taxpayers.”

The Department for Transport said Cook would provide his final analysis “in due course”.

The shadow chancellor, John McDonnell, said he was “staggered” by the reported figures and branded it “another failing” presided over by Grayling.

McDonnell said: “It just demonstrates that the government has lost control of this project – well, lost control over all of its transport policies. It’s another failing by Grayling, by the looks of it.

“We’re [the Labour party] committed to high-speed rail but we’ve said time and time again that we will ensure that we review all of the costings and make sure that we have tighter control than this government has. It’s a shock.”

Last week HS2 announced that it had abandoned its initial hunt for a contractor to build its station at Birmingham after companies were unwilling to take on the risks associated with the £435m projected cost. HS2 said it would rethink the procurement process for the new Curzon Street station.

It comes after Andy Burnham, the mayor of Greater Manchester, called for a “Crossrail for Manchester-type scenario”, where lines would be built under the centre of the city to help people cross it.

Speaking at an event on Friday about the future of rail in the north of England, he said: “The government always seems to run out of money by the time they reach the north. Why are they trying to build HS2 on the surface here? The only answer I can give you is: because they can.”