Conservative MP Jonathan Sayeed has been suspended from the House of Commons for two weeks.
Mr Sayeed already had the Tory party whip withdrawn for a month
It follows a probe by a Commons watchdog into claims he was paid for tours around the Palace of Westminster.
A report said his conduct "has fallen well below the standards" expected and risked harming the Commons' reputation.
Mr Sayeed had denied the claims, saying the suspension was "unjust and wrong" but he made an "unreserved" apology to MPs in the Commons chamber.
He insisted that the report by the Standards and Privileges Committee had contained a "few errors of fact".
Committee chairman Sir George Young said he and colleagues would now have to consider whether Mr Sayeed's remarks constituted a full apology.
That came after Mr Sayeed said: "I accept that a complaint was brought because of ineffectual internal controls in a company in which I had an interest and that as an MP I was negligent in not checking the actions of that company.
"For that I unreservedly apologise to the House."
Michael Howard had already suspended him from the Tory group of MPs for a month for his "completely unacceptable" behaviour.
"Such behaviour in a Conservative Member of Parliament is completely unacceptable and I condemn it without hesitation," said Mr Howard.
The MP now faces a possible deselection bid after his Mid-Bedfordshire constituency association called a special meeting for 17 February.
Association chairman Ashley Green told BBC News: "We will be considering Mr Sayeed's future."
The inquiry was sparked after allegations in the Sunday Times claimed "The English Manner Ltd charges clients up to £500 per day for access to the Palace of Westminster through Jonathan Sayeed" - a charge rejected by the MP.
The firm, which organises luxury holidays in Britain for rich Americans, was set up by Mr Sayeed and his Commons assistant.
Mr Sayeed was accused of abusing his position as an MP by entertaining customers in the Commons.
The committee concluded there was no evidence that he had directly received fees for hosting them in the House.
But both Mr Sayeed and his assistant Alexandra Messervy were "at the least negligent in failing to exercise sufficient care to safeguard the reputation of Parliament", the MPs said, "and at worst have acted carelessly, in a manner which has allowed that reputation to be injured".
The Tory MP told colleagues he had no longer had shares in the English Manner and had resigned as a consultant.
"I can assure the House that I have never used my access to the House or its facilities for direct or indirect commercial benefit and I have never solicited or received any payment for any tour or entertainment within the Palace of Westminster," he said.
Mr Sayeed has been MP for Mid-Bedfordshire since 1997; before that he represented Bristol East from 1983 to 1992.