A Chinese state-owned energy giant, which is investing in a major new nuclear plant in the UK, is facing espionage charges in the United States after allegedly conspiring to steal American technology.

China General Nuclear Power (CGN) is accused of recruiting American engineers to pass them the valuable secrets and threatening U.S. security. One of their senior advisers, Szuhsiung Ho, is a naturalised U.S. citizen and is due in court next week.

In one email from 2009, Mr. Ho allegedly wrote: “China has the budget to spend. They want to bypass the research stage and go directly to the final design and manufacturing phase,” The Times reports.

The case follows an investigation by the FBI and is being prosecuted by the National Security Division of the Department of Justice.

CGN has a 33 per cent stake in the £18 billion Hinkley Point project in Somerset, southern England, which was signed by Chinese president Xi Jinping during an official state visit to the UK in 2015 designed to cement a “Golden Era” with Beijing.

The rest of the investment is due to come from French energy firm EDF, which is controlled by France’s socialist government.

The American indictment says that CGN’s board of directors is “comprised of members of the Communist Party of China” and is under the “direct control” of a state-owned Commission described as Beijing’s “highest government authority”.

The deal, which effectively hands control of vital infrastructure to the communist power, has been heavily criticised from the beginning and the UK’s new prime minister Theresa May recently delayed final approval citing security concerns linked to China’s involvement.

Under the deal signed by President Xi, China would also back a plant at Sizewell, Suffolk, before progressing to a fully Chinese-designed and built plant in Bradwell in Essex.

“When we were in government Theresa May was quite clear she was unhappy about the rather gung-ho approach to Chinese investment that we had,” Britain’s former business secretary Vince Cable told BBC Radio.

Nuclear engineer Mr. Ho, 66, was born in China but became a naturalised American citizen and ran a consultancy called Energy Technology Int. He is now accused of recruiting six U.S. nuclear experts to supply secret information to the Chinese company.

He is in prison after being arrested in April and is due to appear before a court in Knoxville, Tennessee, on Tuesday seeking bail.

Paul Dorfman, of the energy institute at University College London, told the Times: “This extraordinary case demonstrates that concerns over involving China in UK critical nuclear infrastructure are clear and present.

“So it may well be in our own best interest not to allow CGN, or any other Chinese nuclear state entity, access to our key nuclear infrastructure and markets.”