Neither BWEA nor BP was willing to comment but one BWEA member, who asked not to be named, welcomed the move, saying BP was a "missing part of the jigsaw". Shell has been a member for some years and other big power producers, such as Centrica, owner of British Gas, E.ON of Germany and Scottish Power, have also joined.

BP has no wind farms in Britain and very few such assets outside, apart from a couple of experimental plants in the Netherlands. But it established an alternative energy division last year and has set itself ambitious targets to develop solar and other operations.

Wind power in Britain was boosted last month when a number of projects were approved. But the £1.5bn London Array - the largest offshore wind scheme in the world - is still being held up by the refusal of campaigners in Kent to agree to a vital electricity sub-station.

A boom in demand for wind turbines has pushed up equipment costs by 30% and led to shortages. Chris Shears, chairman of the BWEA, described it as "the best and the worst times" for the industry.