Labour rocked as Brown is forced to repay £12,000

But Labour MP Jim Devine, who referred himself to police over allegations surrounding his own expenses claims and was banned from representing the party at the next election, has been vindicated by independent auditors.

Read Peter Facey's analysis of this story here

Meanwhile, Chancellor Alistair Darling, who changed the designation of his home several times, has been asked to submit proof of his mortgage payments on his second home.

His spokeswoman said he was sending the papers immediately, and she added that he had paid back 554 for a chest of drawers, as the 1,104 piece of furniture was over a 550 limit.

Both Conservative leader David Cameron and Liberal Democrat leader Nick Clegg were also tainted by the expenses furore. Mr Cameron has been ordered to provide more details of a 218.91 mortgage overpayment, while Mr Clegg has paid back 910 in excessive gardening bills.

The Prime Minister's extraordinary bill from auditor Sir Thomas Legg – for cleaning services, gardening and decorating over the past six years – was almost three times as much as he had been expected to pay back.

The demand is particularly embarrassing for Mr Brown, as he ordered Sir Thomas, a former civil servant, to conduct the audit of all MPs' expenses. Mr Brown had also charged taxpayers twice for redecorating his Fife home. His spokesman said he "apologised for the inadvertent error".

Livingston MP Mr Devine was referred to Labour's "star chamber" after he was accused of submitting a bogus claim for electrical work at his flat.

Questions were also raised about 66 metres of office shelving, said to have been provided by the landlord of his local pub, for which he charged the taxpayer 2,326.

Last night, Mr Devine threatened legal action against the Labour Party.

"I have a lawyer who is foaming at the mouth to challenge the Labour Party for submitting someone to the star chamber," he said. Mr Devine added that, while he had been given a clean bill of health, others "remain in the Cabinet even after they have paid back 12,500" – a clear dig at Mr Brown.

A letter from Sir Thomas told Mr Devine that he had not identified any need for repayments.

Last night, former independent MP and sleazebuster Martin Bell said he was shocked at the revelations about Mr Brown's repayments.

"You would expect better from a party leader and Prime Minister. He is right to pay it back, but he should never have claimed it in the first place.

"This does make his position more difficult," Mr Bell said. "We expect more from our leaders."

Nervous MPs were expecting to receive the letters last night, but the leaders were all given early copies.

Mr Cameron said that Mr Brown's bill was "rather large" and added that all MPs had to abide by the rules. "I've said to my MPs that everyone must take part in this new process, must respond to the letter and must of course comply with the eventual determination of how much money is paid back," he said.

He added: "It is difficult process, but it's got to be dealt with.

"We've got to clean up our politics, we've got to demonstrate that we're dealing with the problem of the past, and that is all the inaccurate claims that were put in, in the past."

Mr Clegg warned MPs not to dispute any "reasonable" repayment request and said his cheque was already in the post.

"This is the first day of parliament after a ridiculously long summer recess, and there is no point having MPs quibbling over every single request from Sir Thomas Legg," he said.

"We have got to move on. If we are going to be able to look voters in the eye at the next general election, we are going to have to clean up the whole system, repay the money Sir Thomas asks for – where those requests are reasonable – and do the radical things, for instance taking MPs out of the property game altogether."

He said: "That is not going to be possible if there is going to be this pitched battle between MPs and Sir Thomas Legg. That's why I chose immediately to pay the money back."

A letter from the Prime Minister's office made clear that he wanted all ministers to comply with Sir Thomas's requests.

He wrote to all members of the government urging them to respond promptly to any requests for further information and to make "appropriate repayments" when the process was complete.

The Prime Minister wrote: "The past system of expenses has comprehensively failed, and we have taken action to completely replace it."

A statement from his private office insisted that Mr Brown would co-operate fully. The statement read: "Mr Brown's expenses have always been cleared by the House authorities as entirely consistent with the rules."

It added: "Mr Brown has written to all ministers, urging them, where they are asked, to respond promptly and in full to any requests for further information, and, when the process is completed to make appropriate repayments."

Graham Paul, a partner and employment law specialist at Dundas & Wilson, said legally MPs should "sit tight", but ethically they would probably be better off paying.

He said: "If you have been claiming expenses from an employer whose interpretation of the rules turns out to be wrong, there is no prospect of them recovering that money from you.

"From a legal position, they should sit tight, but for the sake of their reputations, they probably have no choice but to pay."

MPs have three weeks to respond to issues raised by Sir Thomas.