The House of Commons has launched a last minute attempt to prevent full details of MPs' expenses being published.
A freedom of information tribunal ruled last month that the Commons must release details of the second home allowance of 14 MPs', including Gordon Brown, Tony Blair and David Cameron.
The Commons had until this Thursday to launch an appeal and it had been thought the details would be released unchallenged.
Publication would allow the public to access information including what prominent MPs spent on soft furnishings and the size of their mortgage.
But the Commons today said disclosure raised security concerns for the 14 MPs involved, which also include former deputy prime minister John Prescott, shadow Cabinet members George Osborne and William Hague and former Liberal Democrat leader Menzies Campbell.
A Commons spokeswoman said publishing the details, which would include details of MPs' home addresses, risked "inhibit[ing] democratic debate" on sensitive issues.
"The threats that MPs can face are unpredictable and subject to change," she added.
The Commons said the information tribunal's ruling also gave "insufficient attention to the reasonable expectations of MPs".
The case will now be heard by the high court, prolonging the three-year freedom of information battle.
A separate freedom of information request on the expenses of six MPs will also be appealed by the Commons.
The information commissioner said the six, including Mr Blair, Mr Brown, Michael Howard and Charles Kennedy, should release details of their travel expenses, staffing, IT provision, stationery, incidental expenses and amount listed under additional cost allowance.