Call for inquiry over MPs for hire

David Cameron has demanded an investigation into "shocking" claims that senior Labour MPs were offering expertise for cash.

The Tory leader joined cross-party condemnation of former ministers who were caught in an undercover "sting" operation for a television documentary.

Labour was forced to rush forward promises to enforce a compulsory register of lobbying planned in its election manifesto.

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But Mr Cameron said the claims raised wider questions about whether the MPs had broken sleaze rules and urged the Prime Minister to probe potential breaches within the Government itself.

"These are shocking allegations. I have been warning for some time that lobbying would be the next scandal to hit politics," the Tory leader said.

All of the MPs filmed, including former cabinet ministers Stephen Byers, Patricia Hewitt and Geoff Hoon, denied any wrongdoing and insisted they had breached no rules.

But Cabinet ministers said the behaviour of former colleagues had been "appalling" and "ridiculous" and Liberal Democrat leader Nick Clegg called it "very, very sleazy".

Mr Byers was among retiring MPs interviewed by an undercover reporter posing as the representative of a fictitious US lobbying firm.

He told an undercover reporter he had secured secret deals with ministers, could get confidential information from Number 10 and was able to help firms involved in price fixing get around the law.

The Sunday Times, which carried out the interviews with Channel 4's Dispatches programme, said Mr Byers, who held several key cabinet portfolios such as trade and transport, wanted 5,000 a day.

The North Tyneside MP retracted his claims – insisting he had "never lobbied ministers on behalf of commercial interests" and had exaggerated his influence. But there were immediate demands by opposition parties and a trade union for an inquiry into a series of policy changes that Mr Byers, who called himself "a cab for hire", said he had secured.

Among Mr Byers's boasts was that he had come to a secret deal with Transport Secretary Lord Adonis over the termination of a rail franchise contract and that Business Secretary Lord Mandelson had got regulations on food labelling amended after he intervened for a supermarket giant.

All parties firmly denied the claims but the Tories and Liberal Democrats said they would table a series of Parliamentary questions seeking clarification.

Mr Byers also faces being reported to the Commons sleaze watchdog but said he was "confident" he would be cleared by any investigation.

Ms Hewitt, a former health secretary, said she "completely rejected" the suggestion that she helped obtain a key seat on a Government advisory group for a client paying her 3,000 a day.

The work under discussion would have been taken up after she stepped down as an MP, she pointed out.

Mr Hoon was reported to have wanted a 3,000 a day to turn his political knowledge and contacts "into something that frankly makes money".

An Commons committee called more than a year ago for a compulsory detailed register of all lobbying to be overseen by a powerful watchdog.