The former deputy chair of the Oakervee Review into HS2, Lord Berkeley, has claimed that the project is likely to spiral to more than £108bn, compared with HS2’s official budget of between £81bn and £88bn.

In a “dissenting report” published on the project, Berkeley says there is “overwhelming evidence” that the costs of HS2 are “out of control” and that its benefits have been vastly overstated. A vocal critic of HS2, Labour peer Berkeley said MPs had been “misled” about the price of the project, which was set at £55bn in 2015.

The government downplayed Berkeley’s claims, saying that they were his personal view and his criticisms of HS2 have also been comprehensively rejected by a coalition of northern political leaders and businesses. “We need HS2 and Northern Powerhouse Rail delivered together, in full,” said the leader of Manchester City Council Sir Richard Leese, part of the Connecting Britain campaign.

Lord Berkeley says that there is little prospect of HS2 trains running between London and Birmingham before 2031 and he also warned that high-speed trains will not reach Manchester and Leeds until 2040. According to the official timetable for the project, trains are due to start running on HS2 between London and Birmingham in 2029.

Speaking to the BBC at the weekend, Berkeley said that it was much more important to spend money on improving rail services in the north of England. “That's where the really bad quality railways are,” he said arguing that a complete upgrade could probably be done at half the cost of HS2.

Responding to his report, Midlands Connect director Maria Machancoses commented: “Lord Berkeley’s suggestions that the government should consider building only small sections of HS2 in the north of England shows a disgraceful ignorance of how important the scheme is to the Midlands. Our region of more than 10 million people stands to benefit the most from HS2, yet we are consistently squeezed out of the debate. HS2 must be delivered in full.”

Rail Industry Association chief executive Darren Caplan called for the publication of the Oakervee Review “as soon as possible”. “Let us be clear, HS2 is vital for the UK as it seeks to boost its transport infrastructure for the whole country in the coming decades,” he said. “It will provide much greater capacity by taking traffic off the current rail network, and transform connectivity between economic centres, cities, towns and communities. It is already generating thousands of jobs, and billions of pounds and GVA in investment and economic growth across the country and will do even more in the coming months and years as the project gets delivered,” said Caplan.

The prime minister Boris Johnson has said that the future of HS2 will not be decided until the Oakervee Review into the project is published. As yet, a publication date for the review has not been announced.