French electricity giant EDF said Wednesday that completion of a new nuclear power plant in southwest England would be delayed by six months and run another 500 million pounds ($687 million) over budget.
The Hinkley Point project, which is supposed to provide seven percent of Britain's total power needs, has been dogged by spiralling costs since the British government signed up for it in 2016.
"The start of electricity generation from Unit 1 is now expected in June 2026, compared to end-2025 as initially announced in 2016," said a statement from the company.
"The project completion costs are now estimated in the range of 22 to 23 billion pounds", it added, up some around 500 million pounds (565 million euros) from figures last given in September 2019.
EDF said its announcements followed "a detailed review... to estimate the impact of the (coronavirus) pandemic so far."
British signed a deal with EDF and its Chinese partner China General Nuclear Corporation (CGN) in 2016 for a project that was initially meant to cost 18 billion pounds.
Critics have focused on the proposed design, which uses a new European Pressurised Reactor (EPR) system that has been beset by huge cost overruns and delays at sites in France and Finland.
Britain's National Audit Office (NAO), a public spending watchdog, has long criticised the scheme, saying the government has "locked consumers into a risky and expensive project with uncertain strategic and economic benefits".
Heavily-indebted EDF, mainly owned by the French government, is funding around two-thirds of the cost of the project and its Chinese partner the remainder.
Similar problems to those at Hinkley have hit EDF's project at Flamanville in western France, although the firm has successfully launched two reactors with Chinese partners in Taishan, China.
In September, Japan's Hitachi scrapped its multi-billion-pound nuclear plant project in Wales in face of the deteriorating investment environment, in a major blow to Britain's atomic energy programme.