A Japanese court has blocked the restarting of two nuclear reactors in the western city of Takahama, after local people raised safety concerns.
The plant had already obtained approval from the country’s nuclear watchdog.
But locals had petitioned the court in Fukui prefecture, where Takahama is located, to intervene, saying it would not withstand a strong earthquake.
All 48 commercial reactors in Japan remain offline following 2011’s Fukushima disaster.
The BBC’s Rupert Wingfield-Hayes in Tokyo says the ruling is a serious blow for Prime Minister Shinzo Abe’s push to have the reactors restarted.
Mr Abe has said the shutdown is damaging the struggling economy, forcing Japan to import expensive fossil fuels to make up the power shortfall.
The operators of Takahama plant, Kansai Electric, said the plant met heightened safety standards brought in by the Nuclear Regulation Authority (NRA) after Fukushima.
But the court agreed with nine local residents who filed an injunction, and ruled that the company had been overly optimistic in assuming that no major quake would hit the region, national broadcast NHK reports.
It also criticised the NRA safety standards as “lacking rationality”.
Kansai Electric said it was considering appealing against the ruling.
Before the accident, caused by a massive quake and tsunami, about 30% of Japan’s power was nuclear generated.
So far only two reactors - in Kagoshima prefecture in the far south - have been approved for restart. They are expected to become operational later this year, but this move is also being challenged in court.