The comments follow today's (Tuesday) announcement from EDF that it plans to scale back on preparatory work for the project and reduce the number of people working on it in a bid to control costs.

On behalf of 21,000 Prospect members working in nuclear decommissioning and energy supply, National Secretary Alan Leighton said: "Our members' fear that any delay in the preparation work could impede or delay EDF's ability to bring the project to fruition once agreement has been reached.

"Prospect is committed to an appropriate energy mix for the UK, including gas and renewables, but it is undoubtedly the case that nuclear and nuclear new build will be pivotal if we are to achieve the twin goals of capacity and security of supply.

"We hope that this announcement will encourage all involved in the talks to redouble their efforts to agree a strike price. Particularly as it comes so soon after the recent warning from outgoing Ofgem head, Alistair Buchanan, that we are facing an imminent capacity crunch in the UK unless urgent action is taken.

"Without an agreement we risk losing a once-in-a-generation opportunity to meet the country's decarbonisation targets and help build a new economy that provides good quality jobs and growth for the UK."