Warren Buffett, the US billionaire investor, could bow out of the battle for Constellation Energy after his MidAmerican Energy utility group said it would not try to outbid EDF of France.

Constellation’s directors were due to meet Tuesday to decide whether to accept a $4.5bn offer from EDF for 50 per cent of its nuclear power generation business or go with a rival lowball $4.7bn offer from MidAmerican for the whole group.