In a banqueting suite at Blackburn Rovers’ stadium in April 2004, Labour MPs and local dignitaries gathered to celebrate the formidable rise of Jack Straw from earnest MP to the consummate cabinet minister.

Four years on, Straw, now the justice secretary and lord chancellor, faces questions over the sponsorship of the event and his own judgment, with the confirmation that an international energy company donated £3,000. The gift was not declared to the Electoral Commission or the parliamentary authorities.

At the time, Canatxx Energy Ventures was lobbying for a controversial scheme to develop a gas storage facility under the Wyre estuary, in a constituency close to Straw’s in Lancashire.

The company’s donation to Straw’s party in 2004 is under scrutiny because it plans to resubmit its application for the proposed gas project in the next few weeks. A complaint has now been sent to Westminster’s standards watchdog and the Electoral Commission.

Under the laws relating to political donations, constituency parties and MPs must declare all donations larger than £1,000. This includes contributions towards a function.

Ben Wallace, the Conservative MP who is opposing the scheme in his constituency and has filed the complaints, said: “Not only should this money have been properly declared, but Straw should explain why he considered it appropriate to accept money from an energy company wanting to build a gas storage facility that was strongly opposed by the local community.”

A spokesman for Straw said he had never had any involvement with Canatxx’s business. He said he had disclosed the sponsorship in a parliamentary answer in 2006, but added that questions over whether there had been any breaches of rules were a matter for the Electoral Commission and the parliamentary commissioner for standards.

Straw was elected to parliament in May 1979 for Blackburn. Twenty-five years later, on April 24, 2004, he held a party at Ewood Park, the stadium of Blackburn Rovers football club, to celebrate his anniversary.

Diners were shown pictures of the highlights of Straw’s political career while enjoying a meal prepared by caterers from Northcote Manor, one of the finest restaurants in Lancashire. Among the guests were John Hutton, now defence secretary, Sir Gerald Kaufman, the veteran Labour MP, party officials from the constituency and key community figures.

Tickets cost £25 a head but Canatxx Energy Ventures, the British offshoot of the American energy company of the same name, also provided sponsorship. Lord Taylor of Blackburn, a Labour peer who acts as an adviser to Canatxx, was among the guests.

A spokesman for Straw confirmed last week that the firm had sponsored the event with a £3,000 donation, but it is unclear where the money was paid.

Michael Poultney, who was treasurer of the Blackburn Labour party in 2004, said he had not registered any donation from Canatxx with the Electoral Commission because, as far as he was aware, the money had not gone through the local party’s bank account.

He said £10,200 in revenue from ticket sales had gone through the party accounts, but that was subsequently paid to Straw’s constituency office to meet the costs of the event.

MPs are required to disclose any donation that might be linked to membership of the House of Commons in its register of interests.

Wallace believes Straw has breached parliamentary rules.

Canatxx, which has offices in Lancashire, first submitted an application to create a gas storage facility in salt caverns in Fleetwood, Lancashire, in November 2003 to the Labour-controlled Lancashire county council.

The firm said the facility would increase Britain’s gas storage capacity by 20%.

The project, however, is opposed by some residents who are anxious it would have an adverse impact on the environment and wildlife.

Campaigners have also raised safety concerns, pointing to a disaster in 2001 involving a similar underground storage plant in Kansas, in which a gas leak led to a series of fires and explosions, killing two people. Canatxx had no link to that tragedy.

Ian Mulroy, who chairs the protest group Protect Wyre, said: “There is genuine fear about this project. We don’t believe it is safe. I am very disappointed Jack Straw accepted their sponsorship.”

Britain has limited storage capacity for gas and Whitehall initially broadly supported the project. The trade department wrote to Lancashire council in May 2004 supporting the scheme and its potential contribution to the “national security of gas supply”.

After a planning inquiry, the scheme was rejected by Hazel Blears, communities and local government secretary. She said there was a lack of robust geological modelling, an inadequate understanding of risk and uncertainty regarding noise impact.

Canatxx now believes it has addressed the issues raised during the planning process, including the safety concerns.

The company confirmed this weekend it had donated £3,000 for Straw’s anniversary party, but said it was considered a “non-political” donation.

It said it had made a range of other community donations, including Christmas lights for Fleetwood, football shirts for a local team and charitable gifts.

A spokesman for Straw said: “It was Jack Straw himself who told Mr Wallace in a parliamentary written answer more than two years ago that Canatxx had been one of the sponsors of the dinner to mark his 25 years as MP for Blackburn in 2004.

“Mr Straw volunteered the information to Mr Wallace despite it not being relevant to the question which had been asked. Mr Straw had no connection with Canatxx before the dinner, and has had none since.”

He said Straw and the Blackburn Labour party would make available any document required for an inquiry.

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