A total of 27 MPs are letting out property they have in London while claiming Commons expenses to rent homes, it has emerged.
An investigation by the Daily Telegraph using parliamentary records found former ministers were among the group that received taxpayer funding to live in the capital.
The move does not break any parliamentary rules but is likely to fuel calls for expenses rules to be toughened up.
Research by the Press Association found that shadow ministers Andy Burnham and Chris Bryant, and Tory MPs David Amess and Liam Fox receive income from letting out flats in London while also claiming expenses for renting in the city.
The Telegraph also named former defence ministers Peter Luff and Sir Nick Harvey among the 27.
Luff declined to comment on the claims but according to the paper, he lets one small residential property in London he owns jointly with his wife but also claimed £17,799 in expenses for rental payments in the last financial year.
Concerns have also been raised that a "loophole" in the rules allows MPs to profit by renting properties to colleagues, who then claim the costs on expenses.
It is understood that four MPs are currently renting from other MPs - although there are no cases of home "swaps".
Linda Riordan, the Labour MP for Halifax, rents her London flat to fellow Labour MP Iain McKenzie for £18,720 a year, according to the Daily Mail.
McKenzie told the paper: "If I had know beforehand that the flat was owned by an MP then I probably wouldn't have taken it.
"You've got to apply the test of how it looks to the man in the street, regardless of whether it's above board or not."
Yesterday Commons Speaker John Bercow was accused of trying to suppress details of the matter after warning the Independent Parliamentary Standards Authority (Ipsa) that revealing the identities of politicians' landlords would be a "security risk".
Ipsa had been due to disclose the material in response to a Freedom of Information (FOI) request.
However, the process has now been put on hold in the wake of Mr Bercow's intervention.
In a letter to Ipsa, Mr Bercow insisted there was a "very real danger" that MPs' residential addresses could be discovered as a result of the planned publication.
Tory Sarah Wollaston said she had grave concerns about revealing MPs' addresses, having had her London flat and constituency home broken into.
The Totnes MP said she agreed with the need for transparency, but was worried about a tiny minority of people, including activists, using the information maliciously.
Dr Wollaston said: "I am very happy for everyone to know that I have no connection with my landlord in my London address - I have never met them and I don't think they even live in this country.
"But if they (Ipsa) publish politicians' home addresses then you are exposing them (MPs) to very difficult situations."
Matthew Sinclair, chief executive of the TaxPayers' Alliance, said: "If MPs are again found to have exploited the expenses system, it will be another stain on the reputation of Parliament.
"It was the cry that 'it's all within the rules' combined with attempts to suppress the publication of claims that made the MPs' expenses crisis three years ago so toxic. Whilst the rules may not technically prevent MPs from renting properties to one another, it is certainly against the spirit of those rules.
"The public's faith was left in tatters in 2009 and the latest allegations could endanger much of the work that has been done since then to restore public confidence in our politicians.
"It is vital that there is total transparency in all matters relating to MPs' taxpayer-funded expenses and allowances."
An Ipsa spokesman said: "We are committed to transparency as is shown by our regular publication of all claims by all MPs. We have a duty to balance that against the risk of compromising security.
"We are currently going through the process of gathering all the relevant information to get that judgment right."
Responding to the Speaker's letter, Sir Ian Kennedy, chairman of Ipsa, insisted the authority "would not, under any circumstances, release the full address" of an MP.
But he added: "The policy also makes clear that we would release, on request, the names of landlords and other suppliers of goods and services where this was in support of a claim made under the Scheme for Business Costs and Expenses."
Sir Ian said all affected MPs had been contacted, asking if they had concerns about the release of their landlord's details.
However, only a third - 110 - had replied. Some 60 have indicated they have no problems with the disclosure, and 50 expressed reservations.
"We are therefore delaying our response to the FOI request and will be writing to those MPs concerned to give them a further two weeks to respond," he said.