Japan on Friday restarted its third nuclear reactor since a country-wide shutdown in the wake of the Fukushima disaster, after a court ruled it was safe despite opposition from local residents.

The government and utility firms have been pushing to get reactors back in operation nearly five years after a huge earthquake and tsunami caused a disastrous meltdown at the Fukushima nuclear power plant.

The accident forced all of Japan's dozens of reactors offline for about two years in the face of public worries over the safety of nuclear technology and fears about radiation exposure.

Kansai Electric Power's No. 3 reactor at its Takahama nuclear plant in Fukui prefecture, northwest of Tokyo, was switched on Friday afternoon, a company official said.

The Fukui District Court last month overturned an injunction preventing Kansai Electric from restarting two reactors won by local residents, who argued it was not proven to be safe despite a green light from the national Nuclear Regulation Authority.

Kansai Electric -- which Bloomberg News reported was the most dependent on nuclear power of all of Japan's utilities before the Fukushima meltdown -- plans to restart the No. 4 reactor in late February, the official said.

Two reactors in the southern prefecture of Kagoshima, operated by Kyushu Electric Power, restarted in August and October, ending a two-year hiatus in nuclear power generation.

But many Japanese remain wary of nuclear power and thousands have refused to return to areas hit by the Fukushima meltdown over fears of radiation exposure.

Friday's restart drew immediate criticism from anti-nuclear campaigners.

"Allowing the restart of the Takahama reactors with potential fire safety hazards that would pose significant risk of reactor core meltdown is irresponsible," Kendra Ulrich, senior global energy campaigner at Greenpeace Japan, said in a statement.

"Once again, it may be the people of Japan who end up paying the price for their government's nuclear gambling."