Japanese Prime Minister Yoshihiko Noda met anti-nuclear demonstrators face-to-face on Wednesday for the first time since weekly rallies outside his office began five months ago.

About a dozen representatives of the movement asked Noda to reverse his decision to restart two reactors and urged him to abandon nuclear power altogether.

Thousands of people regularly turn up in central Tokyo's government district to demand an end to atomic power, with distrust of the technology running high after the 2011 Fukushima disaster.

"People keep coming to our weekly rally," Misao Redwolf told the premier. "That's because anger is ballooning as you restarted nuclear reactors despite the fact that the Fukushima disaster has not been resolved yet."

Another demonstrator pointed out that Japan is surviving its oppressively hot summer with just two reactors online, proof that the resource-poor country can do without nuclear power.

"We will never, never, never, never give up until nuclear reactors are stopped. And on top of that, we will never forget the Fukushima disaster and its victims," said another demonstrator.

Noda told the protesters his government was considering its energy policy with a view to "phasing out nuclear power in the mid to long term."

He said the decision would be made taking people's views and the need for a stable supply of energy into account.

Demonstrators have been asking for a meeting with Noda for some time, while the government has struggled to develop a united position on the prickly issue.

Weekly protests began in March with organisers claiming tens or even hundreds of thousands of people at each event, although police estimates of the turnout are usually considerably lower.

Opinion polls show a majority of voters would like to see a phasing out of Japan's reliance on nuclear power, which provided almost a third of the country's electricity until the tsunami-sparked meltdowns at Fukushima.

The government is expected to draw up plans for Japan's future energy mix as early as this month.

Options under discussion range from nuclear providing around 30 percent of the country's needs to there being no atomic power at all.

Under a zero-nuclear scenario, government experts have forecast Japan's economic growth could be hampered.

But industry minister Yukio Edano said earlier this month that Japan could phase out nuclear power by 2030 without damaging the world's third-largest economy.

Senior members of Noda's Democratic Party of Japan are leaning towards a zero-reliance option as they struggle to earn public support ahead of a seemingly inevitable autumn election.