A Labour minister has been criticised for using taxpayer allowances to fund a second house in London when her family home is eight miles from Westminster.

Dawn Butler, a junior whip, claimed almost her entire £23,000 allowance to help to pay for a second home in her constituency in northwest London. Opposition MPs demanded to know why she needed the taxpayer to help to buy another property when she could stay overnight in her family home in East London.

A review of MPs' allowances and expenses will begin in the autumn, conducted by the Committee on Standards in Public Life, the sleaze watchdog. This is the third investigation of the way MPs claim expenses since January 2008, when it emerged that Derek Conway, a Tory MP, was wrongly paying his son from his expenses budget. The committee, chaired by Sir Christopher Kelly, will not report until after the next election.

Senior committee sources have told The Times that a new administration would provide the best opportunity to push through reforms that may be unpopular with MPs. Yesterday Gordon Brown urged the committee to widen its inquiry to look at MPs' second jobs and outside interests.

The issue of MPs' second-home allowances reignited after Tony McNulty, the Employment Minister, admitted claiming £60,000 on expenses on his parents' Harrow home, which he owns. He later criticised the rules that allowed him to make the claims.

Mr McNulty is now facing an inquiry from John Lyon, the Parliamentary Commissioner for Standards, after a complaint from Greg Hands, a Tory Treasury spokesman.

Two dozen MPs with seats in Greater London claimed almost £400,000 of public money to fund second homes in the latest year for which figures are available.

They include Ms Butler, who has a family home in Stratford, East London, and another in Wembley, in her Brent South constituency. The Stratford property is eight miles and a 24-minute Tube ride away from Westminster. The Wembley house, bought after the election, is nine miles and a 32-minute Tube ride away from the Houses of Parliament.

Ms Butler claimed £15,442 from the Commons in property costs in 2005-06 and £21,803 last year. The arrangement has been approved by the fees office. Her spokesman has previously justified the claim by saying: “When she was elected she moved straight into the constituency and the[ [allowance] helps her to do that.”

Norman Baker, the Liberal Democrat MP, said: “It is difficult to see how an MP having two homes equidistant from Westminster helps them with their duties.”

Many other outer London MPs have been criticised before for their decision to take the money, which almost half of them turn down.

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