Lib Dem Nick Harvey, who helped draw up tougher rules, said the vote created a "real headache" for those trying to rebuild public confidence.

External auditing and spot checks were "absolutely vital", he said.

More than 30 ministers were among those rejecting tougher rules. Some argued external audits would be too costly.

Proposals to change the system were drawn up after a five-month inquiry by the Members Estimate Committee, chaired by Speaker Michael Martin, after Tory MP Derek Conway was reprimanded for overpaying his son for Parliamentary work.

'One-way argument'

They included an end to the so-called "John Lewis list" - the use of public money to pay for items like new kitchens and household goods such as TVs - and replaced the additional costs allowance, used to cover the cost of running a second home.

And they called for spot checks and external auditing of MPs expenses.

Mr Harvey told BBC Radio 4's Today programme both measures were "absolutely vital" to try to rebuild public confidence in Parliament.

"The fact that the public's hard-earned money can be used for MPs to buy and then indeed own a plasma television is just a one-way argument in public perception that we were never going to win," he said.

'Real headache'

He added: "MPs are the only people in the country who sign off their own expenses."

Asked about one newspaper headline, suggesting MPs had voted to "keep their snouts in the trough", Mr Harvey said: "It's very, very hard to see how we are going to tackle that perception because a set of rules to try and bring everything under control was put up and has now been voted down.

"And I think collectively we've got a real headache as a result of the vote yesterday."

On Thursday, following debates on pay and expenses, MPs voted by a majority of 28 to retain the additional costs allowance, and to have their spending looked at only by internal, rather than external, auditors.

More than 30 government ministers, including Home Secretary Jacqui Smith, Culture Secretary Andy Burnham and Northern Ireland Secretary Shaun Woodward, voted to keep the old allowance.

Gordon Brown was not at the vote - the Conservatives accused him of "going awol (absent without leave)" and "showing blatant contempt for very real public concerns". The shadow cabinet voted for the tighter system.

'Great cost'

Labour MP David Winnick said it had been a "missed opportunity" which "gives the impression of an abuse of public expenditure".

But Labour former minister Peter Kilfoyle rejected the notion that by opposing the new rules he had voted to keep the "John Lewis list" - saying that was something drawn up by Commons officials not MPs.

He told the BBC he was very concerned about teams of external auditors "at very great cost" being able to "to trawl through individual MP's office".

Mr Kilfoyle said all receipts were audited in the Commons fees office adding: "Why should someone come round my office and do an effective time and motion study on my staff - when I'm technically self employed?"

There were also questions about whether the new system might be too bureaucratic - and who would police a new overnight allowance - to be claimed for every night they stayed in London.

MPs' expenses came under scrutiny after the Derek Conway case and a Freedom of Information tribunal ruling that details of MPs' second homes allowance claims should be published.

An information tribunal criticised the existing rules as "deeply unsatisfactory", said checks were "very limited" and said the "laxity" rules was "very different" from those in the private sector.

Some new rules have already been brought in. MPs employing relatives have begun declaring them and MPs must now submit receipts on all items worth more than £25 - previously they could claim up to £250 without providing a receipt.

Sir Christopher Kelly, chairman of the Committee on Standards in Public Life, last week questioned whether even the new rules went far enough.

Asked about Thursday's vote to reject reforms, he said: "I would expect the public to react very badly."

BBC