The move could damage the credibility of the committee's inquiry, as the use of gas for electricity generation is widely blamed for the decline of the coal industry.
It emerged yesterday, meanwhile, that British Coal has admitted privately to the select committee that it has allowed a coalface at Silverhill colliery, Nottinghamshire, to deteriorate beyond repair, despite a pledge to the High Court that it would not jeopardise the possibility that 10 pits scheduled for early closure could resume production at the end of statutory 90-day consultations.
British Gas said there had been discussions with Dr Clark - also chairman of the former Energy Select Committee - but that nothing would happen while the Commons inquiry into pit closures was continuing.
British Gas, like many North Sea producers, has contracts to supply gas to new Combined Cycle Gas Turbine electricity generating plants. The growth of those CCGT plants is almost entirely at the expense of older, coal-fired power stations.
Dr Clark became an adviser on energy matters to British Gas in August, although the formal working relationship was dropped because of the coal inquiry. He is seen as politically useful to British Gas, and may rejoin the company as an adviser in the new year.
He has been an outspoken critic of the Government's lack of a cohesive energy policy and its attitude to the energy industry. He lobbied fiercely for the survival of the Energy Select Committee, even though the Department of Energy was absorbed into the Department of Trade and Industry this year.
It is thought that he has come under pressure from other members of the Trade and Industry Select Committee to declare his potential interest. Strictly, he need not do so until his British Gas appointment is confirmed.
The implications for the Committee's inquiry are unclear. Dr Clark's contribution has been regarded as particularly valuable as he is one of few members of the committee to have wide experience in the energy sector.
Results of the Government's inquiry into 21 of the 31 proposed closures and overall energy policy are due to be published early next year.
The select committee has expressed concern that its report, also due out then, should be accorded equal weight.
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