Parliament's sleaze watchdog is to investigate expense claims made by Culture Secretary Maria Miller.
John Lyon, Parliament's Commissioner for Standards, will look at a complaint about the senior Tory minister's second home allowances.
The decision to investigate follows revelations that Mrs Miller claimed more than £90,000 for the cost of a house her parents had apparently been living in.
She received £90,718 between 2005 and 2009 - almost the maximum allowed - for mortgage payments, bills and other costs at the property in south London.
Labour MP John Mann filed a complaint earlier this week, arguing the arrangement was "identical" to that of ex-Labour minister Tony McNulty.
Mr McNulty had to pay back more than £13,000 in expenses in 2009 because they were spent on a second home occupied by his parents.
The Commissioner ruled in that case the MP had effectively "subsidised" his relatives from the public purse, allowing them to live rent free.
Mrs Miller insisted on Sky News earlier this week that her claims were "absolutely as they should be".
A spokesman added on Thursday: "Mrs Miller's expenses have been audited twice and found to be wholly proper and above board.
"Any suggestion to the contrary is simply untrue. She would fully co-operate with any inquiry."
David Cameron insisted Mrs Miller did an "absolutely excellent job" as Culture Secretary and declared she has his full support.
"A newspaper has asked her a number of questions. As far as I can see she has excellent answers to all those questions and I am sure she will answer them and get on with her job, which is what she should do," he said.
The minister's claims were originally revealed by The Telegraph, sparking a row with the Government amid claims aides had tried to suppress the story.
Mr Cameron's head of communications Craig Oliver and Mrs Miller's special adviser Joanna Hindley have been accused of using the Leveson report to put pressure on the newspaper.
The Telegraph claims Ms Hindley referred to the report, apparently in an attempt to threaten them, when she was called for a response to the expenses revelations.
Mr Oliver then also mentioned the issue in a telephone call to the newspaper's editor - reportedly saying "she is looking at Leveson at the moment".
Number 10 has insisted Mr Oliver was only highlighting concerns about how the paper pursued the story because it had spoken to the minister's elderly father.
Mrs Miller has since insisted the affair has nothing to do with the Leveson report. "My concern is that any investigation is done in accordance with the rules, the Editors' Code," she said.
The Telegraph said it had lifted the lid on the conversations behind the scenes to show the risk of politicians being involved in how the press is regulated.
:: Further cross-party talks on press regulation on Thursday broke up without agreement amid continued divisions over the need for a system backed by law.