David Cameron reprimanded a Conservative backbencher who claimed yesterday that MPs were victims of a “McCarthy-style witch-hunt” over their expenses claims.

Nadine Dorries said there were fears that an MP would commit suicide. The situation at Westminster had become “completely unbearable”.

Mr Cameron told the BBC: “Of course MPs are concerned about what is happening but, frankly, MPs ought to be concerned about what their constituents think and ought to be worrying about the people who put us where we are.”

There was clear anger among the Tory leadership at the latest intervention by the outspoken Ms Dorries, MP for Mid Bedfordshire, with one senior source describing her comments as “completely wacky”.

There is growing frustration within the party that the row has stalled the Conservatives’ momentum as they approach a general election.

According to one Tory source, party officials have rebuked Ms Dorries on more than one occasion for her “increasing tendency to make wild and eccentric statements”.

After Ms Dorries had drawn a comparison between the row over MPs’ expenses and the anti-Communist witch-hunts of Senator Joseph McCarthy in the United States of the 1950s, a number of other MPs criticised her intervention.

Stephen Pound, a Labour MP, described her comments as facile. “The idea that anybody is going to play the violin and ask people to contribute to the MPs’ relief fund [shows] absolutely no grasp of reality whatsoever,” he said.

Speaking on the BBC Radio 4 Today programme, Ms Dorries had said: “People are seriously beginning to crack. 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 have 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.”

In yesterday’s interview, Ms Dorries insisted that the underlying problem was not the greed of politicians but 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 new MPs were advised by Commons officials that they had an absolute right to claim the full additional costs allowance.

“Prior to my intake in 2005 MPs 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’.”

The Archbishop of Canterbury, writing in The Times, says that tighter rules are not enough to restore the public’s faith in politicians. Dr Rowan Williams says that public service should reflect values of integrity.

A Labour MP who claimed parliamentary expenses on a flat where his daughter lived became the fourth yesterday to be referred to the party’s “star chamber” to decide whether he should be deselected as a candidate in the general election. Ian Gibson has already said that he is ready to stand down if voters in his Norwich North constituency want him to.

It was disclosed yesterday that Dr Gibson received almost £80,000 in second home expenses on a West London flat that he later sold at a knockdown price to his daughter and her partner. He insists that the claims were legitimate, as he was staying at the flat on three nights a week, but acknowledged that the arrangement might seem “unfair” to voters.

Labour’s national executive panel is already looking into the cases of Elliot Morley, David Chaytor and Margaret Moran, and will hold some hearings next week.

Georgia Gould, daughter of Tony Blair’s polling guru, Lord Gould of Brookwood, hinted that she might try to stand in a seat vacated by one of the Labour MPs forced to stand down over the scandal. She said that she was the victim of a “vicious smear campaign” to prevent her from being selected as Labour’s candidate in Erith & Thamesmead.

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