The comments follow media reports that seven global electricity and nuclear companies have written a joint letter to the prime minister threatening to withdraw from plans to invest millions in energy infrastructure.

They call for a long-term stable policy framework to provide the confidence needed to secure the funds to back low-carbon development. The letter comes shortly after John Cridland, director general of the CBI, warned that a return to an over-reliance on gas would be a mistake.

On behalf of 21,000 members working in nuclear decommissioning and energy supply, Prospect General Secretary Designate Mike Clancy said: "We have long warned that action needs to be taken to provide business with the incentives and confidence to engage in the long-term nature and scale of investment required. Maybe now that industry and the CBI are echoing that call the message will get across?

"Achieving a balanced low-carbon energy supply is an essential step to building a new economy that provides good quality jobs and growth for the UK. But it is not achievable via the market alone. The time for procrastination is over. We need to act now or risk driving international companies to more hospitable investment climates abroad."