Under pressure MP Simon Danczuk has condemned the "poorly worded" expense rules which "punish modern families" after it emerged he is being investigated over his accommodation claims.
The twice-divorced politician is alleged to have received thousands of pounds of funding for his children to stay at his flat - even though his eldest son said he had only ever visited him there once.
The Independent Parliamentary Standards Authority (Ipsa) - which regulates expenses - allows MPs to claim up to £2,425 extra a year towards accommodation costs for each dependent.
The watchdog - which was set up in the wake of the expenses scandal in 2009 - said this is designed to give MPs the ability to rent flats with more than one bedroom to "main contact with their families during the course of their parliamentary work".
But Ipsa compliance officer Peter Davis announced they had launched a formal probe in Mr Danczuk’s circumstances after a member of the public made a complaint.
The father-of-four said his original claim "was made properly and based on my honest interpretation of the Ipsa regulations".
He said: "I maintain that the existing rules are poorly worded and not fit for purpose when it comes to modern families like mine.
"Some of my Parliamentary colleagues have approached me in the last week to say they agree with me on this point and that they have interpreted the rules the same way.
"I'll be meeting with the chief executive of Ipsa about this and I will stress the need for the system to be more flexible to reflect the living arrangements of modern families.
"I am co-operating fully with the investigation and welcome the chance to get this matter cleared up."
He has two children with his first wife Sonia Rossington and two with second wife Karen Danczuk - with whom he separated last year.
Mr Danczuk is currently suspended from the Labour party over separate allegations that he exchanged "explicit text messages" with a teenager in his Rochdale constituency.
Additional reporting by PA
