Conservative leader David Cameron has removed the whip from backbencher Derek Conway as controversy over alleged overpayments continued today.
Mr Conway faces a ten-day suspension from the Commons chamber after the standards and privileges committee found he had paid his son an unreasonably high salary for little apparent work.
Mr Conway was forced to apologise "unreservedly" to the house for what he described as his "administrative shortcomings". The committee had found his son Freddie, who was studying at Newcastle University during the time he was supposed to be working for his father, had had "little or no contact" with Mr Conway's office.
A statement from Mr Cameron said: "The usual procedure in these cases is to leave the punishment to the House of Commons authorities.
"However, having asked the chief whip to speak again to Mr Conway and having personally reflected overnight I have decided to withdraw the Conservative whip from Mr Conway."
The BBC reported the MP for Old Bexley and Sidcup describing Mr Cameron's decision as "understandable". It means he is no longer a member of the Conservative parliamentary party.
The latest development does not put the issue at rest, however.
The Liberal Democrats' prospective parliamentary candidate in Mr Conway's constituency, Duncan Barrowman, has written to the Metropolitan police requesting that they investigate the case.
And Labour MP John Mann has announced his intention to file a second complaint against Mr Conway, relating to payments to a second son - Henry - who worked for his father before Freddie's employment.
Speaking on the Today programme this morning, Mr Mann said: "If he's been doing the same thing with the first son that's a significant sum of money that needs to be paid back to the taxpayer, but it also puts the pressure on David Cameron.
"He needs to say today what he's going to do about Mr Conway. Should he be a candidate for the Conservatives at the next election, and should he be maintaining the Conservative whip?"
Mr Mann later criticised Mr Cameron for delaying the decision to withdraw the whip, saying he had only sacked the backbencher because he had become "a PR problem".
Tory backbencher Roger Gale defended Mr Conway on the Today programme as "a good constituency member of parliament and an honourable man".
He pointed out many MPs employ their family as staff "for very good reasons" and said Freddie Conway's son would have had his employee contract scrutinised by parliament's fees office.
Liberal Democrat justice spokesperson David Heath said the authorities should take action to "allay public concern" over the issue.
He called for auditors to be given powers to carry out spot-checks on MPs' expenses, as recommended by the senior salaries review body, and said it was "perfectly proper" for a list of all those employed by MPs to be disclosed.