SECRECY laws understood not to have been used since the Iraq war are believed to be in place to stop the publication of a high-speed rail project report.

Transport secretary Patrick McLoughlin is said to have invoked the secrecy laws to prevent publication of an HS2 Project Assessment Report produced by the Major Projects Authority.

Action groups campaigning to stop the £50billion rail link have reacted by suggesting the report is being withheld as it is ‘damning’ for sections of the government.

Richard Houghton, of HS2 Action Alliance, said: "Secrecy and withholding of information kills governments - especially in an era when public and business alike are deeply suspicious of politicians.

“That is something which should be carefully considered not just by the current government, but any likely future Labour-led government.

"We obviously have not had access to the MPA report into HS2, although as with everything of this nature there are leaks and rumours.

“These lead us to believe that the report is damning and could see heads rolling in both the Department for Transport and other sections of government.”

Mr Houghton believes the proposed project will blight 500,000 homes, of which he predicts 2 per cent will receive compensation, and generate massive environmental damage.

"We cannot work out how a MPA Project Assessment Report is not in the public interest,” he added.

“Independent research says the majority of the population does not want HS2, so why shouldn’t the public know what the MPA has to say on its viability?”