Jack Straw strongly denies any wrongdoing
The justice secretary faces questions over a £3,000 donation from an energy firm which sought planning permission close to his Blackburn constituency.
Canatxx Energy Ventures contributed to a party in 2004 marking Jack Straw's 25 years as an MP, the Sunday Times says.
A Tory MP has asked the Parliamentary Standards' watchdog to look into the payment, which the paper claims has never been officially declared.
Mr Straw says he has been open about the money. He denies any wrongdoing.
The Sunday Times says Canatxx was involved in a plan to build a £300m underground gas storage facility in Lancashire, close to Mr Straw's constituency.
Conservative MP Ben Wallace asked a parliamentary question in 2006 about whether Mr Straw, the then foreign secretary, had accepted hospitality from Canatxx.
He received the response: "No. The honourable member might however wish to be aware that Canatxx was one of the sponsors of a dinner in April 2004 to mark my (then) 25 years as member for Blackburn. My department was not involved in any way in this event."
The Mr Wallace has now requested that the Electoral Commission and the Parliamentary Standards Commissioner look into the payment, which the newspaper claims was not recorded in the registers of MPs' interests or donations to parties.
A spokesman for Mr Straw said the suggestion that he had been involved in any planning decisions was "a very serious allegation" and one he strongly denied.
Mr Straw had always been open about the energy company's role in sponsoring the 2004 event, and mentioned it in the parliamentary written answer in 2006, he said.
"Mr Straw has never had any involvement with Canatxx's business whatsoever. Not before the event referred to, during it or after it."
Gas storage plans
He said Mr Straw understood from the Sunday Times that Mr Wallace had referred this matter to the parliamentary commissioner, but that the justice secretary had not been been contacted about it by Mr Wallace himself.
"If this is the case, any requests from the parliamentary commissioner for any records relating to this event will of course be made available by Blackburn Labour Party and Mr Straw," he added.
Canatxx had its plans to store gas in salt caverns beneath the Wyre estuary at Preesall turned down last year.
Lancashire County Council rejected the proposals on grounds of their environmental impact and the potential risk of gas leaks.
The firm, which has registered offices in Kirkham, Lancashire, plans to submit a new planning application in the next few weeks.