UNDER-FIRE SPEAKER TO STEP DOWN !

Watch Mr Martin's statement live on this page at 1430 BST

Michael Martin is set to announce he will stand down "soon" as Speaker in a Commons statement to MPs at 1430 BST.

Mr Martin has been criticised over his handling of the furore over MPs' expenses and a motion of no confidence in him has been backed by 23 MPs.

It will be the first time in 300 years that a Speaker has effectively been forced out of office.

Sources have told the BBC that Mr Martin also will trigger a by-election by standing down as an MP.

Officials in his Glasgow constituency are preparing for a summer poll.

Meanwhile, Gordon Brown said no Labour MP who broke expenses rules would stand at the next election.

And former Conservative minister Douglas Hogg has said he will stand down as an MP at the next general election.

He has already agreed to repay £2,200 - the cost of clearing a moat at his country estate - which had been on paperwork submitted to the Commons fees office in support of his claims.

Tory backbencher Douglas Carswell - who put forward the motion of no confidence in Mr Martin - said the Parliamentary system had fallen into disrepute with many MPs being seen as "parasites" over the expenses scandal.

But he told the BBC: "Removing Michael Martin is not the end, it is the beginning - a new Speaker has to be reformist, they need to be progressive."

Mr Martin, the MP for Glasgow North East and Speaker since 2000, is due to meet party leaders later to discuss interim reform proposals for MPs' expenses.

A spokeswoman for the Speaker confirmed Mr Martin was making a statement this afternoon "about himself" and would be going ahead with the meeting at 1630 BST.

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Asked whether the Speaker had resigned the prime minister's official spokesman said: "That is a matter for the Speaker."

Mr Martin's critics say he was the driving force behind repeated attempts by Commons authorities to block details of MPs' expenses from coming out under Freedom of Information legislation.

He was also criticised for attacking MPs in the Commons who had campaigned for more transparency or questioned his decision to call police to investigate the leaking of expenses details to the Daily Telegraph.

On Monday Mr Martin said he was "profoundly sorry" for his part in events but did not give any indication of - or timescale for - any plans to stand down.

He was challenged by a succession of MPs who stood up to ask when they could debate a motion of no confidence in him.

Liberal Democrat leader Nick Clegg had openly called for him to go - calling him a "dogged defender of the status quo".

Prime Minister Gordon Brown and Tory leader David Cameron had said it was a matter for the House of Commons - not the government or official opposition.

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Labour MP Sir Stuart Bell, a member of the ruling House of Commons Commission, said he hoped MPs would respect what Mr Martin had to say and recognise his "great service" to Parliament.

"I think the turning point for the Speaker in his own mind would have been the order paper today which had stark reading about a vote of no confidence - and reading today's newspapers, building up on what happened yesterday, I think made his statement inevitable," he said.

"But he is determined to see through the reforms that he announced yesterday."

He also said reforms approved at the cabinet meeting earlier - to put independent regulators in charge of the Commons - meant the role of the Speaker would change.

"There will no longer be a Speaker who is in charge as chief executive of the House of Commons. He will be procedural and ceremonial - so when we do look for a new Speaker it will have to take that into account.

Mr Carswell's motion of no confidence in Mr Martin was put on the order paper on Tuesday.

But former Tory minister Peter Bottomley had tabled an amendment, saying that the Speaker himself is "best placed to decide when to retire from office".

Mr Bottomley told the BBC it would have set an "undesirable precedent" if the issue had gone to a debate and it was right he should be able to announce his own retirement.

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Labour MP David Winnick, who was among those asking Mr Martin to take early retirement on Monday, said: "That is the right and honourable course to take. His resignation will be the first step in the House recovering its reputation."

However fellow Labour MP Austin Mitchell said he had been the victim of a Conservative "witch hunt" and he hoped Mr Martin would not stand down until the next general election. "It's not his fault," he told the BBC.

Former health secretary Frank Dobson said most MPs had backed efforts to keep the expenses system secret.

He told the BBC: "I think it is a dreadful example of the House of Commons as a whole - which as a whole is responsible for the mess we are in - trying to scapegoat one man who was trying to represent what he thought were their views on what should be done."

Meanwhile Metropolitan Police Commissioner Sir Paul Stephenson said the force was working with the Crown Prosecution Service to investigate whether MPs had broken any laws.

BBC NEWS REPORT,