A controversial project by French energy giant EDF to build two nuclear reactors in Britain has become "more difficult" following the country's vote to leave the European Union, France's finance minister said on Wednesday.

"It is more difficult," Michel Sapin told the BBC, adding that the French government however was still committed to the Hinkley Point project going ahead.

"We have to see where we are, we have to recover our balance. Brexit has made waves," Sapin said on the Newsnight programme.

The planned nuclear plant at Hinkley Point in southwest England has been billed as a crucial part of Britain's future energy supply.

But critics say it is too expensive.

A joint project between EDF and China General Nuclear Power Corporation, it carries a projected price tag of PND 18 billion ($24 billion, 21.7 billion euros), making it one of the world's most costly nuclear power plants.

Unions at the majority state-owned EDF have sought to delay committing to the project due to concerns that it could bankrupt the company, which has more than 37 billion euros in debt.