Alistair Darling claimed living allowances for his grace-and-favour home in Downing Street while also claiming expenses for a flat he was letting out to tenants, it was claimed last night.

The latest details will increase the pressure on the Chancellor, who was already facing calls to resign from senior Liberal Democrats over his taxpayer-funded living arrangements.

In July 2007, ten days after he became Chancellor, Mr Darling claimed £1,004 for a service charge on his flat in South London which was to cover the six months to December 2007, The Daily Telegraph reported. It was at that time that Mr Darling moved into his grace-and-favour home in Downing Street and began claiming living allowances.

Mr Darling reportedly makes about £5,000 per year in rent from his South London flat after mortgage costs. He bought the flat for £226,000 in 2005 and claimed £6,000 for carpets and furnishings and £2,260 for stamp duty. Parliamentary rules state that an MP may not claim on more than one property at a time.

Last night a spokesman for the Chancellor categorically denied that there had been any wrongdoing or breach of the rules. “The allegation of double claiming is simply untrue. He paid the bills due for his flat until he moved out in September 2007, after which he made no further claims for it,” he said.

Mr Darling has faced accusations of being a “serial flipper” who has switched his designated second home three times in four years, and is also accused of claiming back expenses for paying an accountant to complete his tax returns.

Before last night’s revelations Vince Cable, the Liberal Democrat Treasury spokesman, said: “Here is the company finance director caught with his fingers in the till He doesn’t explain. He doesn’t apologise. He just blames his colleagues for not stopping him. His moral authority has vanished. He must go, now. We need a Chancellor focusing on the national accounts rather than his own.” Nick Clegg, the party leader, said it was “impossible” for Mr Darling to continue in his job.

There have been suggestions in recent days that the Prime Minister is preparing to replace Mr Darling with Ed Balls, the Schools Secretary. It is understood that any move would be unrelated to expenses claimed by Mr Darling, and that he would most likely be offered the post of Home Secretary.

David Cameron was caught up in the expenses row yesterday after questions over a £350,000 interest-only mortgage that he took out to buy a house in Oxfordshire when he became an MP in 2001. A Tory scrutiny panel is to examine whether he acted unreasonably in using his own money to pay off £75,000 from his London home mortgage rather than using the money to reduce his taxpayer-funded loan.

Had Mr Cameron done so, he could have saved the public about £22,000 in mortgage payments, it is estimated.

Last night Mr Cameron promised to repay £22,000 of expenses if he is found to have behaved unreasonably.

The Telegraph also reported that Michael Howard, Mr Cameron’s predecessor as party leader, claimed £17,000 over four years for “gardening services” at his second home in Kent.

The latest revelations come after a weekend of new details about claims submitted by MPs, including £5 claimed by Frank Cook for a donation he made at a Battle of Britain memorial service. Yesterday Mr Cook apologised and explained that the claim had been submitted in error.

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