The Information Commissioner Christopher Graham says that a report from the Major Projects Authority should be made public.
It comes after Transport Secretary and former Cannock miner Patrick McLoughlin used a veto previously deployed to stop publication of Iraq war papers.
Mr McLoughlinhad overruled the Commissioner's decision to disclose the report under the Freedom of Information Act. Mr Graham has decided on legal action following the Court of Appeal decision in the case brought by Guardian journalist Rob Evans against the Attorney General's refusal to disclose letters written to ministers by the Prince of Wales.
The Commissioner has now written to Sir Alan Beith MP, chairman of the Justice Committee, saying he has decided to apply for judicial review.
He has told Sir Alan the information in the vetoed review 'is all environmental information', and his June 2013 decision notice requiring its disclosure was issued under the Environmental Information Regulations 2004.
HS2 is set to cut a 45-mile swathe through rural Staffordshire from Lichfield to north of Stafford.
Demands are also being made for the suppressed report o be made public by leading politicians in Staffordshire.
George Adamson, leader of Cannock Chase District Council, is calling on Transport Secretary Patrick McLoughlin to publish a report that the government has refused to release.
Mr Adamson said: "How can we make a proper judgment on whether HS2 is right for this country or not if we are not allowed to have the full facts. This is a railway not national security.
"Patrick McLoughlin is a Staffordshire lad and he is letting us down by preventing us from having the truth."
Richard Houghton, of HS2 Action Alliance, said: "So far as we can see, the last time secrecy laws of this nature were invoked was during the Iraq war. The implications are immense.
"Independent research says the majority of the population does not want HS2, so why shouldn't the public know what the report has to say on its viability?"
A Government spokesman added: "It's important to strike a balance between the benefits of transparency and protecting the ability of officials to 'speak truth to power'.
"The Major Projects Authority will not be truly effective if officials fear that their frank advice to ministers could be disclosed.We have already published project-level data in our annual report of major projects and have no plans to go further.
"The Government has decided that it is not in the public interest to release this report."
The boss of HS2 Sir David Higgins has proposed a speeding up of the building of the £50 billion line through Staffordshire by six years by 2027 instead of 2033.
In the report he calls for the first phase of the project to be extended to a hub station in Crewe – which includes the route through Birmingham and Staffordshire – and be completed by 2027 to speed up benefits in the north.
He also called on the government to reconsider the link between HS2 and HS1, stating it is outweighed by the need for more connections between northern cities.