The chairmen of House of Commons select committees may be barred from holding outside commercial interests relating to their committee's area of interest following allegations that Tory MP Tim Yeo used his position to help business clients.
Speaker John Bercow has asked the Commons Standards Committee to consider whether there should be new rules governing the business interests of committee chairmen.
Yeo confirmed yesterday he was standing down temporarily as chairman of the influential Energy and Climate Change Committee while the Parliamentary Commissioner for Standards investigates claims that he "coached" a client on how to present evidence to the committee.
While Bercow stressed he was not seeking to pre-judge the commissioner's inquiry into Mr Yeo - who strongly denies any breach of Commons rules - he said he believed the case had created a "reputational issue" for the House.
Writing to Standards Committee chairman Kevin Barron, Bercow said: "Last November, I mentioned to the Government Chief Whip and the Parliamentary Commissioner for Standards my concern, on behalf of the House, about what many might regard as an inherent incompatibility between chairing a select committee and having commercial interests, even though fully transparently registered, in the sector covered by that committee.
"At present, chairs of select committees are required simply to register such interests, but they are not prevented from having them.
"As I believe that there is a reputational issue for the House involved, I should be most grateful if your committee would consider this specific and important matter, with a view to making a recommendation to the House.
"Colleagues would then have the opportunity to decide whether to maintain the status quo, or to introduce a new rule on the subject."
Yeo - who has declared a series of directorships and shareholdings in companies involved in the "green" energy sector in the Register of Members' Interests - stepped down after an undercover Sunday Times investigation appeared to show him claiming he could exert influence behind the scenes for private companies.
The newspaper's footage showed the MP seemingly suggesting he had coached a client on how to influence the committee when he appeared before it - a hearing at which he excused himself from asking questions because of the conflict of interest.
Following the newspaper report, Mr Yeo referred himself to Parliamentary Commissioner for Standards, Kathryn Hudson, to investigate whether there had been any breach of Commons rules.