While both Tony and Cherie Blair earn more than £100,000 a year and have taken a series of free luxury holidays in recent years, they complain because rules force them to pay for many Downing Street functions from their own pocket.

Mrs Blair's income as a barrister is understood to have fallen by more than half from the £250,000 she reportedly earned before her husband became prime minister.

Foreign trips such as the recent visit to South Africa often require a new range of outfits

She also feels obliged to splash out on expensive designer clothes after the press took her to task for perceived frumpiness in the past.

Friends quoted in a number of newspapers on Tuesday explained the couple feel they must look their best when representing Britain abroad and provide first-class hospitality to visiting dignitaries and other guests - but they pay for these perks themselves.

"Tony spends a heck of a lot of his own money performing his role and Cherie has to spend a fortune on outfits for public engagements," one said.

"She knows if she does not she will be criticised in the media for looking frumpy."

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In advance of the Blairs recent trip to the Commonwealth Heads of Government meeting in South Africa, Mrs Blair bought a series of new top-of-the-range outfits, including one top for £400.

She also flew her personal hairdresser Andre to Durban with her, which reportedly cost at least £3,000 for his ticket alone.

Downing Street sources point out the prime minister draws only £109,768 from his total salary of more than £154,000.

Cherie Blair dresses in a bindi for a Hindu ceremony

But despite this he feels obliged to pick up the tab after most functions to entertain celebrities such as Oasis guitarist and songwriter Noel Gallagher, fashion designer Alexander McQueen, BSkyB executive Elisabeth Murdoch and Virgin boss Chris Evans - just some of the names who have passed through the doors on Number 10 in the past two years.

While Mr Blair clearly regards this type of entertaining as part of the job, strict guidelines mean only official government functions can be paid for out of taxpayers' money.

Friends said the Blairs rarely cooked for dinner parties with their friends any more, instead being forced to hire in outside caterers because of the pressures on their time.

But a Downing Street spokesman on Tuesday insisted the couple had not instructed friends to make public such complaints on their behalf.

"Mrs Blair has never complained to anyone about the cost of clothes or anything else associated with her support for the prime minister," he said.

"It is fact that there can be high costs involved and that she gets no public money to help with them, but she resents suggestions that she is unhappy with the situation.