EDF Energy has said that on-going problems at the Heysham 1 and Hartlepool nuclear reactors, which were taken offline last month, could keep them out of action until the end of the year.

The power outages have led the National Grid to ‘fast-forward’ an emergency plan to obtain more electricity from other providers.

The two plants have a combined capacity of about 2.4GW; they are out of action at a time when part of the 2GW Ferrybridge coal-fired station is temporarily closed due to a fire.

Energy analysts say that the margin between supply and demand is already very small, due to the retirement of old nuclear and coal-fired plants.