Deadlock in Japan between anti-nuclear activists and advocates of nuclear power deepened on Monday.
Prime Minister Yoshihiko Noda's government had been widely expected to announce a decision on energy policy and a reduction of the share of nuclear power to 15 per cent or less by 2030.
Instead, Noda said he wanted the government to decide the direction of energy policy this week.
"The present situation is that the majority of the people want us to aim at a zero-nuclear society," the Prime Minister told a news conference after formally announcing his candidacy for re-election as Democratic Party of Japan (DPJ) leader.
The government has been drafting a new energy policy since the Fukushima plant was crippled by an earthquake and tsunami in March 2011, the world's worst nuclear accident in 25 years. It had to scrap plans to boost nuclear's share of electricity supply to more than 50 per cent from nearly 30 per cent before the crisis.
The issue could become a focal point of a general election expected within months that Noda's Democratic Party of Japan (DPJ) is likely to lose and the government has wavered over whether to set a timetable for abandoning atomic energy.
"They must feel very threatened by having a policy put in place, even by a party that's expected to suffer a major defeat in the next election," said Andrew DeWit, a professor at Rikkyo University, referring to pro-nuclear power interests.
"I guess they worry that the next government might not want to or be able to roll this back."
Earlier on Monday, Noda said in his platform for re-election as party leader that Japan should aim to abandon nuclear power. But he gave no timetable for doing so.
Noda faces three rivals, but is expected to be re-elected as head of his party, which proposed last week that Japan should move towards ending reliance on nuclear power by the 2030s.
Noda also said Japan should build no new nuclear reactors and strictly apply a law limiting the lifespan of existing units to 40 years. That would bring atomic power's share to around 15 per cent of electricity by 2030 and zero by mid-century.
The Fukushima disaster prompted the shutdown of all 50 reactors in Japan for safety checks.
Noda's decision to approve the restart of two reactors to avoid possible power shortages sparked outrage among anti-nuclear activists. Japan ended voluntary targets to cut power use for the summer last week with no shortages reported.
Signs the government was leaning toward a plan to exit nuclear power by a specific date have triggered a fierce counter-offensive by pro-atomic interests.
Japan's nine regional nuclear utilities and business lobbies argue that abandoning nuclear power in favour of fossil fuels and renewable sources such as solar and wind power will boost electricity prices. That, they say, would make industry uncompetitive, complicate efforts to reduce greenhouse gas emissions and threaten the utilities' financial viability.
Nuclear energy advocates also say dumping nuclear power would annoy Japan's security ally, the United States, the world's largest producer of nuclear power.
"To decide on zero nuclear power would be very tough for Japan's economy now and in the future," Hiromasa Yonekura, head of the Keidanren business lobby, told a news conference. "In addition, I think US-Japan relations would worsen."
Anti-nuclear advocates counter that predictions of damage to the world's third-biggest economy are exaggerated and that a policy shift will create new chances for corporate profits in areas such as renewable energy and energy efficiency.
The push to set a timeline for exiting nuclear power has also run into opposition from the northern prefecture of Aomori, home to a plant to reprocess spent nuclear fuel.
The recycling plant in the village of Rokkasho has yet to begin operating due to technical glitches nearly 20 years after construction began. The prefecture is threatening to send back stored waste if the government abandons the recycling programme.