Gordon Brown says he has more important issues than MPs' expenses to deal with as fresh controversy grew about bills submitted by his transport secretary.
Geoff Hoon insists he broke no rules in claiming second home allowances while living in a taxpayer-funded apartment.
The Prime Minister said his focus was on the economy and fighting terrorism.
Meanwhile, Home Secretary Jacqui Smith is contesting newspaper claims she billed taxpayers £40 for a barbecue in her second home, the BBC has learned.
The minister says she is "just about 100% sure" she did not claim for it, sources have revealed.
The Sunday Express reported she claimed a total of £304 for a barbecue, garden patio set and heater at her family home in Redditch, Worcestershire, which Ms Smith calls her second home.
But Ms Smith said "not all of the expenses" outlined in the newspaper were correct, sources told the BBC.
Meanwhile the prime minister appeared to distance himself from the growing controversy about MPs' expenses, which featured in several other Sunday newspapers.
Questioned at a summit he is attending with other EU leaders Mr Brown said: "I think over the last few days the world has made sufficient advances in how we can deal with the economy, how we can deal with terrorism, how we can deal with security and these are the issues I am concentrating on.
"All these other issues are being dealt with by the Committee on Standards in Public Life".
Kenneth Clarke on the expenses saga
Mr Hoon said he had done nothing wrong by claiming second home allowances for his home in Breaston, Derbyshire while living in a taxpayer-funded apartment in Whitehall.
He lived in the flat in Admiralty House while he was defence secretary and also rented out his own London home while there.
He told the Mail on Sunday: "I was told unless I went into secure premises I would have to have round-the-clock police protection at my home in London and that that would cost the taxpayer a great deal more."
He reportedly said he did "not accept" that he was profiting from the situation.
Meanwhile, the Parliamentary Commissioner for Standards confirmed he is investigating another Labour MP over an allowance claimed for second home in the capital.
The commissioner, John Lyon, has begun an inquiry into Leyton and Wanstead MP Harry Cohen who claims costs for his east London home because he lists a house 70 miles away in Colchester, Essex as his main residence.
The growing row has led to fresh calls for MP expenses rules to be tightened, with Liberal Democrat leader Nick Clegg describing it as "barmy" that ministers could have two homes paid for by taxpayers..
Mr Hoon was defence secretary when the claims were made
Tory frontbencher Ken Clarke said he was "shocked" by recent expenses revelations which made people think MPs were "rogues".
The shadow business secretary implied that as many as a third of MPs could have made questionable expenses claims.
He told BBC One's Andrew Marr Show that "at least two thirds of MPs I hope" were doing nothing wrong on expenses and they were suffering from "an exaggerated public view that they're all thieves, they're all rogues, they're all lining their own pockets".
Chancellor Alistair Darling told the same programme that the recent spate of revelations were "damaging".
He said: "I think we do need to get an outside examination of this and so there are recommendations coming from people who've got no axe to grind. I think that's what the public want, and they want it quickly."
Writing in the Mail on Sunday Conservative leader David Cameron said the problems in the expenses system were shared by all parties.
"We are all implicated and we must all find a solution," he said. MPs needed expenses but there had to be more transparency, he added.
Gordon Brown has suggested scrapping the controversial second home payment for all MPs, in a shake-up of allowances.
The Committee on Standards in Public Life is bringing forward a wider inquiry into MPs' expenses, with a report due towards the end of the year.
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