The plant in Moorside, north-west England, was expected to provide around 7 percent of Britain's electricity when built, but has faced several setbacks after Toshiba's nuclear arm Westinghouse went bankrupt last year.

Following the Westinghouse bankruptcy, NuGen joint venture partner Engie pulled out of the project, leaving the Japanese firm searching for new investors.

Toshiba put NuGen up for sale and South Korea's Korea Electric Power Corp (KEPCO) was chosen as preferred bidder last year, but the process has stalled.

Britain needs to invest in new capacity to replace aging coal and nuclear reactors that are due to close in the 2020s, but large new plants have struggled to get off the ground due to high costs and weak electricity prices.

"Toshiba has pursued a sale of NuGen to KEPCO and the prolonged time it has taken reach a conclusion has required NuGen to undertake a review," a spokesman for NuGen said.

"As such additional options are being pursued for NuGen's future direction to deliver the next generation of nuclear new build in the UK," he said.

NuGen has around 60 direct employees, mostly based in Manchester, while the roles of around 40 contractors would also be placed under a 30 day consultation period later this week, the spokesman added.

Britain's government has yet to announce any kind of deal for the NuGen project.

"We continue to engage with new build developers, though the detail of these discussions is commercially confidential," a spokeswoman for the Business, Energy and Industrial Strategy department said.

Another plant, to be built by a unit of Japan's Hitachi Ltd, has also struggled to find funding, leading the British government to consider direct investment.

However, EDF's Hinkley Point C will be the first new nuclear plant built in the country in more than twenty years after securing additional backing from the French government, investment from China General Nuclear Power Corp, and a long-term power price guarantee from Britain.

The government has been criticised for being too generous in the terms it has set for this deal.

(Reporting by Susanna Twidale; Editing by Alexander Smith)

By Susanna Twidale