Prime Minister Naoto Kan of Japan used the 66th anniversary of the dropping of the nuclear bomb on Hiroshima to repeat his pledge to make the country less reliant on nuclear energy.
Mr Kan called for a review of Japan's energy policy after the earthquake and tsunami, which wrecked the Fukushima Daiichi nuclear power station on 11 March.
Radioactive material is still leaking from the plant.
The BBC reports Mr Kan promised to challenge ''conventional beliefs'' that nuclear energy was safe.
About 30% of Japan's electricity generation was nuclear before the crisis and the country had previously targeted raising that figure to 53% by 2030.
Mr Kan has promised to review energy policy.
''I will reduce Japan's reliance on nuclear power, aiming at creating a society that will not rely on atomic power generation,'' he said.
The prime minister spoke after laying a wreath of yellow flowers at Hiroshima Peace Memorial Park, where doves were released as a symbol of peace.
Thousands observed one minute's silence in memory of the 140,000 killed by the US atomic attack in 1945.