Brussels - European Union regulators approved Britain's proposed $25.7bn nuclear power station to be built by French utility EDF , two sources familiar with the matter said.
The project at Hinkley Point, southwest England, is part of Britain's strategy to replace a fifth of its ageing nuclear power and coal plants and provides a major export contract for France.
The landmark case has been closely watched by pro-nuclear Lithuania and Poland, which want more guidance on the level of state aid allowed for such projects, and by EU countries that are phasing out nuclear energy in favour of renewables, such as Germany.
The European Commission met earlier on Wednesday, with 27 other commissioners set to vote on Competition Commissioner Joaquin Almunia's proposed clearance of the British plan.
"Yes, it's agreed, they voted in favour. The vote was very tight," said one of the sources.
Sources told Reuters last week that a quarter of the commissioners opposed the deal and wanted Almunia to demand tougher concessions from EDF.
Almunia will announce the decision at a news conference at 10:30 GMT. His spokesman Antoine Colombani declined to comment.
The scheme gives EDF a guaranteed power price of €92.50 per megawatt-hour for 35 years, more than twice the current market rate.
The decision of the European Commission, the EU executive, on state aid issues is definitive, but it can be challenged in the European courts.
Austria and green critics, angered by what they say are over-generous terms for EDF, have already said they will take legal action.
"There is absolutely no legal, moral or environmental justification for turning taxes into guaranteed profits for a nuclear power company whose only legacy will be a pile of radioactive waste. This is a bad plan for everyone except EDF," Greenpeace EU legal adviser Andrea Carta said in a statement.