The Prime Minister has defended embattled Commons Speaker Michael Martin, saying "Michael Martin has been a very, very good Speaker."

Mr Martin is under growing pressure after being plunged into a new storm over his expenses.

Critics insist Mr Martin should hand over control of a review of MPs' allowances after more questions have been raised over those claimed by him and his wife, Mary.

His spokesman Mike Granatt has already resigned for "ethical reasons" after he unwittingly misled a journalist over taxi journeys taken by Mrs Martin.

The Parliamentary Commissioner for Standards is being urged to investigate the revelation Mrs Martin was accompanied on the trips by her housekeeper and not a Commons official, as journalists had been told.

Concerns have also been raised over Mr Martin's use of the second home allowance after it emerged he does not have a mortgage on the property but has claimed £75,000 in expenses to maintain it.

He already faces criticism for using air miles earned on official business to pay for flights taken by family members.

The row could not have come at a worse time as he is currently tasked with overseeing the reform of MPs' controversial expenses system.

But Mr Martin receieved another show of support when he was greeted with cheers at the start of parliamentary business.

There was a chorus of "hear, hear" from MPs in the chamber, particularly from the Labour backbenches, to which Mr Martin replied "thank you very much".

But the Speaker still has his detractors. Anti-sleaze campaigner Martin Bell said Mr Martin was being protected from MPs' criticism because they are unable to openly criticise the Speaker.

Mr Bell said: "He is protected by a wall of silence, actually, because MPs can talk about anything they like, inside or outside the House, except their views about the Speaker.

"They do not speak up and we know there is widespread disquiet on both sides of the House and no-one dare speak up."

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