MPs will next week attempt to force Gordon Brown to hold a public inquiry into the Iraq conflict amid widespread anger that a probe announced by the Prime Minister this week will be held behind closed doors.
When he announced the inquiry in the Commons on Monday, Mr Brown insisted that sitting in private was essential to protect national security and to allow the witnesses to be as "full and candid as possible".
But a Conservative motion to be debated next Wednesday says the hearings "should whenever possible be held in public".
Tory leader David Cameron has warned that under the current proposals the inquiry could be seen as an "establishment stitch-up" and Liberal Democrat leader Nick Clegg said: "The Government must not be allowed to close the book on this war as it opened it - in secrecy."
A number of Labour backbenchers joined in the criticism of the inquiry when it was announced in the Commons - and could potentially rebel against the Government to support the Tory motion.
Shadow foreign secretary William Hague said: "There is clearly a widespread dissatisfaction across all parties and throughout the country about the high-handed way in which the Government established Iraq inquiry.
"There is still time for them to put this right and the debate we will initiate next week will give them the opportunity to do so.
"To have real credibility the inquiry needs to be open to the public whenever possible and to have a wider and more diverse membership.
"I hope the Government will come to its senses and listen to the sincere objections being made, seek a genuine consensus and revise its proposals for the inquiry.
"If they do not we will put our motion to the vote in the House."
The inquiry will be chaired by Sir John Chilcot, a former permanent secretary at the Northern Ireland office who was a member of the earlier Butler inquiry into the intelligence on Iraq's supposed weapons of mass destruction.
The other members are Sir Roderick Lyne, a former British ambassador to Moscow; Baroness Prashar, the chairman of the Judicial Appointments Commission and two historians, Sir Lawrence Freedman and Sir Martin Gilbert.
The Tory motion states that the membership of the committee should be "wider and more diverse" and also calls for a parliamentary debate on the inquiry's terms of reference.
Today the head of the Army at the time of the invasion of Iraq joined the criticism.
General Sir Mike Jackson, the, then, Chief of the General Staff, told The Independent that he would have "no problem at all" in giving his evidence in public.
Holding all the hearings in private would, he said, simply feed the current climate of "suspicion and scepticism" about government.
Peers will tomorrow debate the invasion of Iraq and the lessons which can be learned.