A cross-party group of MPs has launched a bid to have the prime minister impeached for "gross misconduct in his advocacy of the case for war against Iraq".

Led by Plaid Cymru MP Adam Price, the campaigners have accused Tony Blair of misleading parliament over weapons of mass destruction.

They have tabled a parliamentary motion formally seeking the impeachment - the first time such a motion has appeared on the Commons order paper in 198 years.

Asked about the MPs' bid the prime minister's official spokesman said: "It is their right to do so. Let's just wait to see what happens."

Among those also backing the bid are SNP leader Alex Salmond, Conservative MP Boris Johnson and Liberal Democrat Jenny Tonge.

No Labour MPs are backing the campaign - any that did are thought likely to face suspension or expulsion from the party.

Former Labour MP George Galloway, who now sits as an independent, is giving his support to the bid.

Price, who commissioned a document setting out the legal basis for the impeachment bid, said the prime minister's dishonesty about the war had "subverted" British democracy.

"We must make a stand or watch the democracy that we have fought for so often against foreign enemies be subverted from within," he said.

"The rules of constitutional conduct have been brushed aside. The Cabinet table has been replaced with the sofa, Cabinet minutes with email, and the facts replaced with 'belief'.

"People say politicians do nothing and are all alike. Today we make a stand for parliamentary democracy.

"We ask our colleagues and the people to help us restore the accountability of the government to parliament."

Motion

The motion but forward by the MPs calls for a select committee to be established to report back to the Commons on "the conduct of the prime minister in relation to the war against Iraq".

It says relevant issues include "the conclusion of the Iraq Survey Group that in March 2003 Iraq did not possess weapons of mass destruction and had been essentially free of them since the mid 1990s".

And it highlighted Blair's "acknowledgement that he was wrong when in and before March 2003 he asserted that Iraq was then in possession of chemical or biological weapons or was then engaged in active efforts to develop nuclear weapons".

Other factors include comments from United Nations secretary general Kofi Annan suggesting the Iraq war was illegal.

The select committee would be tasked with reviewing whether "there exist sufficient grounds to impeach Tony Blair on charges of gross misconduct in his advocacy of the case for war against Iraq and in his conduct of policy in connection with that war".

MPs on the committee would report back within 48 days on "such resolutions, articles of impeachment or other recommendations as it shall think fit".

Under parliamentary procedures it now falls to Commons speaker Michael Martin to decide whether the motion is actually debated.

Powers

Meanwhile Charles Kennedy has called for the creation of a special committee of MPs to investigate the prime minister's powers to declare war.