The pound14.2 billion ($19 billion) investment will end "years of delay and uncertainty", the UK Treasury said in a press release, adding it would unlock a "golden age" of nuclear to "boost the UK's energy security".

The UK is the majority shareholder in the plant being built in eastern England, after Chinese company CGN left the project and the other partner, French energy giant EDF, scaled back its involvement.

The plant, which comprises two EPR nuclear reactors each with 1.6 gigawatts capacity, could cost a whopping total of pound20-30 billion to build.

The sum could be even higher, according to some estimates which are disputed by the government and EDF, and it is not expected to start generating electricity until 2035.

"The government's decision to move ahead with Sizewell C is fantastic news for Britain, its energy security and economic growth," EDF Energy CEO Simone Rossi said.

The latest injection is part of budget announcements by Britain's finance minister Rachel Reeves, who is due to detail her spending and investment priorities for the coming years on Wednesday, with defence and health as key areas.

The UK is now the majority shareholder in Sizewell C, EDF said in January.

With a fleet of ageing nuclear power stations managed by the French energy company, the UK has refocused on shoring up nuclear power since the start of the war in Ukraine, in the name of energy security.

The Labour government, which took over from the Conservatives in July, is following the same line, and says it wants to implement "the biggest nuclear rollout program for a generation".

It also announced on Tuesday in its press release "record investment" in research and development into nuclear fusion of more than pound2.5 billion over five years.

But the announcement has been met with anger by some local residents worried about the impact of the new plant on the local town of Leiston in Suffolk.

Nearby is also the single water pressurised Sizewell B nuclear power station which is currently is due to close in 2035, and Sizewell A which is in the process of being decommissioned.