In a statement to the stock market this morning, the French energy firm said the plant would now be operational until 2030 at the earliest.

The facility, which employs more than 700 people, had been due to be decommissioned in 2023.

It started generating electricity in 1988 and had originally been intended to have only a 30-year operational lifespan.

Torness is one of four of Britain’s nuclear power plants to be given an extended lifeline by operator EDF. The other plants are in Lancashire and Teesside.

EDF Energy CEO Vincent de Rivaz said: “Our continuing investment, our expertise and the professional relationship we have with the safety regulator means we can safely prolong the operating life of our nuclear power stations. Their excellent output shows that reliability is improving whilst their safety and environmental performance is higher than ever.

“In today’s extremely challenging market conditions, our belief that Government policy will be maintained and strengthened gives us the confidence to invest in our nuclear stations. This gives customers the best value low carbon electricity available.

“It’s a great achievement by thousands of EDF Energy staff and partners in the supply chain who have worked so hard to show that we can deliver on performance, reliability and safety.”

EDF also owns the Hunterston B nuclear power station in North Ayrshire, which is due to close in 2023.

A Scottish Government spokesman said the supported life extensions for existing nuclear power stations, “where the environmental and safety requirements continue to be met”.

He added: “Over the coming months we intend to continue work towards an over-arching energy strategy, setting out priorities for the future energy system in Scotland.

“At a time when UK government policy is causing other power stations in Scotland and across the UK to close prematurely and deterring investment in key renewables we will continue to make the point to the UK government that we are very concerned about the security of supply in Scotland.”