A leading backbench MP has alleged that details on politicians' expenses are being offered to journalists for around £300,000.
Sir Stuart Bell (Lab, Middlesbrough) told the BBC that he expects a "drip, drip" of detail about the spending of senior MPs to emerge over the coming weeks.
Commons authorities are now looking into how the details came to be released into the public domain.
And he called for the Committee on Standards in Public Life to "speed up" its inquiry on MPs' allowances.
Sir Stuart also urged all parties to place the recommendations of the inquiry by Sir Christopher Kelly in their manifestos for the next election.
Figures released on Monday revealed that MPs have claimed around £93m in annual expenses.
Members have claimed an average of £144,176 on top of their salaries.
The Daily Mail says that "to add insult to injury", backbenchers are to receive an "inflation busting" 2.33 per cent pay rise from April 1.
But the prime minister has announced that ministers will have their salaries frozen this year.
Speaking at a press conference yesterday, Gordon Brown said: "Their pay has been frozen. That's the right thing to do when people are suffering in the economy."
But there is also growing pressure on one of the highest-claiming MPs, home secretary Jacqui Smith, to resign.
Sir Stuart told the BBC this morning that details of expenses are being "hawked" around Fleet Street for a figure believed to be around £300,000.
"The story was running very thick and fast yesterday in the House of Commons lobby," he explained.
"And the press were onto this. We know that there are leaks because the information on Jacqui Smith was leaked, Tony McNulty was probably leaked and there was other information that will probably come into the public domain.
"We expect this to keep running. We don't believe that the newspaper will buy all of the 365 for £300,000."
But he suggested that there would be "a drip, drip" of expenses claims for senior politicians in the "limelight".
Sir Stuart explained that all receipts are likely to be published by July this year, with over 1.2 million expenses claims laid "on the table".
And he criticised MPs for turning down recommendations last year to end the second homes allowance for outer London MPs. "That is why we are in this pickle today," he said.
Sir Stuart continued: "I would agree entirely with the prime minister. The standards in public life [committee] say that they want their own inquiry.
"We ought to speed up that inquiry. Any recommendations they make should come into force at the next election which is next year as we know."
