The Sunday Times claims the Energy Select Committee Chairman Tim Yeo admitted in secret filming that he coached a paying client on how to influence his committee.
Mr Yeo rigorously denies any wrongdoing.
The paper also says he discussed a fee of £7,000 a day to act as a "paid advocate" for a energy company.
Mr Yeo says he did not accept the offer because he realised it was not permitted under House of Commons rules.
He now plans to refer himself to the Parliamentary Standards Committee.
The Serjeant at Arms is considering "as a matter of urgency" whether staff of All-Party Parliamentary Groups (APPGs) should be given passes to the Houses of Parliament.
It follows the decision to recall 83 passes in the wake of the cash for questions allegations.
A statement from the House of Commons said that the Serjeant, who is responsible for security matters, is looking into whether passes of this kind are "necessary or appropriate".
No passes of this kind will be issued until the matter is settled, the statement said, and if they are issued in future it is likely that applications will require "more information than at present about the purposes for which a pass is required".
Lobbying reforms have caused a political storm in Westminster, with Labour accusing the Prime Minister of undermining the party's trade union support.
Speaking to Daybreak, TUC Assistant General Secretary Paul Novak said: "The Government is using this in a cheap cynical way to score points against the trade unions and the six and half a million people that we represent.
"We think that the trade union money that is in politics, the resources that we put into politics", he added. "That's the most honest money in politics."
The Government will bring forward a bill to introduce a statutory register of lobbyists before Parliament's summer recess in July.Read the full story ›
Speaker John Bercow has ordered the suspension of more than 80 House of Commons passes amid concerns over lobbying, according to Sky News.
The passes were reportedly issued to all-party parliamentary groups (APPGs) of the kind allegedly set up by Tory MP Patrick Mercer after he was contacted by undercover reporters claiming to represent lobbyists seeking to lift Fiji's suspension from the Commonwealth.
A spokesman confirmed the issue was discussed at a meeting of the House of Commons Commission - a committee of senior MPs responsible for the administration of the Commons - but declined to disclose details.
"The commission at its regular meeting tonight discussed the issue of APPGs and will make a statement tomorrow," the spokesman said.
TUC General Secretary Frances O’Grady claims the Government is "cynically trying to exploit a political sleaze scandal to crack down on unions":
Ms O'Grady added, “Making it harder for working people to take strike action and for unions to support local candidates is not the way to clean up politics".
Unite has called the Prime Minister's decision to include curbs on trade union election spending in the lobbying bill "a grotesque insult".
A spokesman for the trade union said: "This is an outrageous attempt to point the finger of blame elsewhere by a Tory Party that accepts more than 50 percent of its funding from a handful of super-rich businessmen".
"Union funding for the Labour Party comes from individual members, ordinary men and women, and is totally transparent.
"How dare this Government suggest that their membership is somehow on the par with a man who defiled the office of MP by hawking himself for a few quid. This is a grotesque insult".
A Labour Party source has called Number 10's lobbying bill announcement "a shabby and panicked response" to this weekend's headlines.
The source said:
The best way to proceed if you want to take big money out of politics and clean up the lobbying scandal is to act on a cross-party basis. Labour has done so.
This seems to be a shabby and panicked response by David Cameron to divert attention from a set of damaging headlines hitting the Conservative Party.
The Government will bring forward a bill to introduce a statutory register of lobbyists before the summer recess, Downing Street has announced.
The bill will also include measures to end self-certification of trade union membership and reform third-party funding of election campaigns.