Mr Martin's report on expenses is due in the autumn Commons response

In the chamber, Labour MP David Winnick asked Mr Martin to show "greater urgency" in conducting his inquiries.

But the Speaker, who has faced pressure to resign over his own expenses, said he would continue as planned "until this House decides otherwise".

Mr Martin had earlier been cheered by MPs at the start of Commons business.

They replied "hear, hear" after Mr Martin, criticised over his use of taxi expenses and air miles, issued his traditional "order, order" call to start the day.

Conway affair'

The Speaker, as chairman of the Commons Members Estimates Committee, is heading a "root-and-branch" inquiry into all aspects of MPs' expenses.

This follows revelations that Tory MP Derek Conway had made payments worth �40,000 to his son for work as a parliamentary researcher while he was a student.

Raising a point of order in the Commons, Mr Winnick, MP for Walsall North, asked the Speaker: "Would it be possible for the review to have greater urgency and not wait until the autumn [for the findings]?"

SPEAKER'S DUTIES Keep order during debates Ensure House rules obeyed Act impartially Represents Commons Chooses MPs to speak Can suspend sittings Protects interests of minorities

He added that recent expenses stories such as those involving Mr Conway had done "damage to the reputation of the House".

Mr Martin replied that he would remain in charge of a review of MPs' allowances "until this House decides otherwise".

He insisted: "And that is a good thing for the reputation of this House."

Labour's John Spellar criticised what he called an attempted "coup" by political reporters.

But a number of MPs are said to want the Speaker to step down as Parliament's standards watchdog investigates a complaint against him.

Mr Martin, MP for Glasgow North East, has been accused of flying members of his family in business class from Glasgow to London for a New Year break, using air miles gained from official trips.

Spokesman resigns

The Sunday Times also reported that he had claimed �17,000 a year for his home in Scotland and �7,500 in costs for using that home as an office.

These figures had been publicly declared already and there is no suggestion Mr Martin used his allowance incorrectly.

The resignation of Mr Martin's spokesman, Mike Granatt, came after he wrongly rebutted a story that the Speaker's wife had claimed more than �4,000 in taxi expenses since May 2004.

Mr Granatt said Mr Martin had not been at fault over the misinformation, and instead blamed officials for not telling him the entire truth.

When asked about Mr Martin's predicament, Mr Brown said: "It's a matter for the House of Commons. Mr Martin has been a very, very good Speaker."

Conservative leader David Cameron said: "I think instead of this speculation about the Speaker and his future, what we should all be doing is actually sorting out the issues that the public want sorted out in Parliament in terms of openness and transparency and getting Parliament in touch with the people."

Liberal Democrat leader Nick Clegg told the BBC there seemed to be "a witch-hunt", adding that the Speaker was "fully committed" to overhauling Parliament's system of expenses.