The MP for Charnwood in Leicestershire is facing a formal investigation over allegations he failed to declare his financial links to care home owners.
It emerged last month that Stephen Dorrell the Health Select Committee chairman, had sold his London home to friends at a reported £70,000 profit, and was using Commons expenses to rent it back.
Mr Dorrell was accused of a conflict of interest because his new landlords run a chain of care homes,
and his committee has been carrying out an inquiry into social care.
A spokeswoman for the parliamentary standards commissioner said he was investigating whether the MP breached rules on declaration of interests