The campaign to expose MPs' Commons expense claims has become so personal that it has started to resemble a McCarthy-style witch-hunt, a Tory backbencher said today.

Nadine Dorries, the Conservative MP for Mid Bedfordshire, also warned that the relentless drip-drip of leaked claims was creating such an atmosphere of terror that there was a real risk of an MP committing suicide.

"People are seriously beginning to crack," Ms Dorries told the Today programme on BBC Radio 4. "The last day in Parliament this week was, I would say, completely unbearable.

"I have never been in an atmosphere or environment like it, when people walk around with terror in their eyes and people are genuinely concerned, asking, 'Have you seen so and so? Are they in their office? They've not been seen for days.'

"There's a really serious concern that this has got to a point now which is almost unbearable for any human being to deal with."

Ms Dorries' comments, echoing postings on her blog, appeared to be part of a fightback by MPs tired of having their reputations dragged through the mud even though they may have broken no Commons rules.

In an angry outburst yesterday one MP who was forced to stand down over the size of his gardening bills complained that his critics had merely been jealous of his "very, very large house".

"I've done nothing criminal, that's the most awful thing," said Anthony Steen, who spent £90,000 his second home, including big sums for lopping trees. "And do you know what it's all about? Jealousy."

Mr Steen was one of two MPs who confirmed their departure at the next election, the other being Ben Chapman, the Labour MP for Wirral South, who insisted that he had done nothing wrong despite allegations that he over-claimed £15,000 extra for mortgage interest.

Mr Chapman said that he had been given permission by the Commons Fees Office to maintain claims on the mortgage for his second home in London despite his decision to pay off £295,000 of it, which reduced his mortgage bill from £1,900 a month to around £400.

Another Labour MP, Ian Gibson, also offered to stand down if the voters demanded it after claims that he had sold his taxpayer-subsidised second home to his daughter at a knock-down rate. He, too, insisted that he acted within the rules.

In this morning's interview, Ms Dorries insisted that the underlying problem was not the greed of politicians but the fact that no Prime Minister in recent history had dared to award MPs a proper pay rise, preferring to use the second home allowance to make up the difference.

The proof, she said, was that until recent years newly elected MPs were advised by Commons officials that they had an absolute right to claim the full Additional Costs Allowance, which she said was a lump sum allowance not an expense account.

"In my intake in 2005 things had changed, but prior to my intake in 2005 MPs were told, they were sat down and told by people in the Fees Office: 'You haven't been awarded pay rises, an MP's salary is not commensurate with anyone else at your professional level, this pot of money has been awarded to you as an allowance, not expenses ... Our job here is to help you maximise that.'"

Under interim reforms announced this week by Gordon Brown and Michael Martin, the Commons Speaker swept from office by the scandal, the Fees Office is to be abolished under a new system of external regulation.

In the meantime, MPs continue to blame it for the more fanciful expenses claims and opaque "arrangements" that have cost them their careers.

The veteran Tory Douglas Hogg, for example, was paid 1/12th of the second home allowance per month to help meet the running costs of his country manor in Lincolnshire, which exceeded the allowance.

Mr Hogg was forced to stand down by David Cameron, the party leader, after it emerged that he had "claimed" for the cost of having his moat cleaned because it was listed on the bills for his estate.

So far one minister, Shahid Malik, has been forced to step down pending inquiries into his claims.

Three Cabinet ministers — James Purnell, Geoff Hoon and Hazel Blears — have been criticised for failing to pay Capital Gains Tax on the sale of their second homes. Mr Brown yesterday gave his full backing to Mr Purnell and Mr Hoon but has called Ms Blears's claim "totally unacceptable".

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