The Labour government has promised to deliver zero-carbon electricity by the end of the decade, and keeping Britain's ageing nuclear fleet operating longer is viewed as critical to meeting the goal.

"These extensions are a major victory for our energy independence," energy minister Ed Miliband said in a statement.

"We can't achieve clean power by 2030 without nuclear, which provides an all-important steady supply of homegrown clean energy," he said.

The nuclear sites Heysham Two, in northwest England, and Torness, in Scotland, will be kept open until 2030, two years longer than planned, EDF said.

Heysham One and a site in Hartlepool, northeast England, will be extended by a year to produce power until March 2027.

EDF said it would invest a further pound1.3 billion ($1.6 billion) at the sites over the next three years, adding to the pound8 billion across the nuclear fleet acquired by the group in 2009.

The extension follows a report from the UK energy system operator, NESO, which outlined that the government's mission to decarbonise the power grid by 2030 is a "huge challenge" but "achievable".

It means the production of electricity, previously dominated by coal and currently reliant on natural gas, would not contribute to overall CO2 emissions.

Wind, solar, nuclear and tidal power would instead generate most of electricity used in Britain from the beginning of the next decade.

Sizewell B, Britain's fifth nuclear power station, also operated by EDF, was not affected by Wednesday's announcement.

However the company indicated that there was also opportunity to extend the lifetime of Sizewell B for a further 20 years to 2055.