Japan on Wednesday inched closer to re-starting idle nuclear reactors, just weeks after the last one was switched off amid public disquiet following the disaster at Fukushima.

Prime Minister Yoshihiko Noda indicated that he was close to giving the green light to units at Oi in western Japan, with opinion coalescing around the need to bring them back online.

"We are beginning to gain a certain level of understanding from the local governments concerned," he said, a reference to the self-imposed restriction of seeking agreement from communities that host the plants.

"Nuclear reactors continue to be important for the development of Japanese society as a whole.

"What comes first is not the restart of reactors but the safety of them.

"I will make a final decision after having discussions with ministers concerned if Fukui prefecture and Oi town reach a conclusion."

Japan's political classes have been tip-toeing around the unpopular issue of reactor restarts for months, in the face of public distrust of the technology since the meltdowns at Fukushima.

Increasingly alarmist warnings of summer power blackouts, with some estimates suggesting certain areas could see electricity supply fall as much as 20 percent short of demand, have added urgency to the issue.

Until the tsunami-sparked meltdowns at Fukushima in March 2011, Japan had relied on nuclear power for around 30 percent of its electricity needs.

But in the months following the world's worst atomic disaster since Chernobyl, reactors that were shuttered for safety checks or maintenance have not been allowed to restart, chiefly because of public resistance.

The country's entire stable of 50 working units are now offline, and none can begin generating power again until it has passed internationally approved stress tests proving its ability to survive a natural disaster.

They must also be given the nod by the host community and get approval from the central government.

The reactors at Oi are so far the only ones that are anywhere near gaining the necessary approval, but the process has become a kind of Mexican stand-off in which neither local politicians nor the central government in Tokyo appears willing to make the first move.

However, on Wednesday night the head of the Union of Kansai Governments, an umbrella organisation which has representation from a range of local authorities in western Japan, indicated some progress had been made.

"We will accept the decision to be made by the government," Toshizo Ido told reporters after a meeting of the union.