China has signed a deal with French energy giant EDF paving the way for Britain's first UK nuclear power plant in a generation.
The investment by Beijing in the new site at Hinkley Point in Somerset, was confirmed as part of a raft of agreements the UK Government hopes will amount to around €40bn.
The announcement was made as the Chinese president Xi Jinping continued his four-day visit to the UK.
However, there are concerns over the security implications of China's involvement in the nation's critical infrastructure.
MI5 has identified spying by Beijing, including cyber espionage, as one of the biggest current threats to Britain's national security.
There are fears China could identify weaknesses at vital facilities, which could then be exploited at a later date using malware.
China General Nuclear Power Corporation (CGN) will have a 33.5% stake in Hinkley Point C, with the rest held by EDF.
The two companies also agreed a wider partnership for the joint development of new nuclear power stations at Sizewell in Suffolk and Bradwell in Essex.