Prime Minister Naoto Kan today took his campaign against nuclear energy in Japan to Hiroshima which 66 years ago became the world's first victim of an atomic bomb.

It marks a change of tack in a country which has until now carefully avoided linking its fast growing, and now discredited, nuclear power industry to its trauma as the only country to have been attacked with atomic bombs.

Kan, speaking at an anniversary ceremony for victims of the bomb dropped on Hiroshima, repeated that the world's worst nuclear crisis in 25 years at Fukushima after a March earthquake convinced him Japan should end its dependence on nuclear power.

The damage from the earthquake and subsequent tsunami at the Fukushima nuclear plant, which the authorities are still trying to bring under control, has led to widespread calls for an end to reliance on nuclear power in the quake-prone country.

"I will deeply reflect on nuclear power's 'myth of safety', investigate thoroughly the causes of the accident and fundamental measures to secure safety, as well as reduce the dependence on nuclear power plants and aim for a society that does not depend on nuclear power plants," Kan said.

Kazumi Matsui, Hiroshima's mayor and the son of an atomic bomb survivor, also pressed Tokyo to act after the Fukushima crisis traumatised the public.

"The Japanese government should sincerely accept this reality and review its energy policy quickly," he said.

It was the first time in decades that any Hiroshima mayor had questioned Japan's policy of developing nuclear energy during the annual ceremony, in which tens of thousands observed a minute of silence as the peace bell tolled.

Matsui said it was heartbreaking to see the devastation left by the March 11 quake and tsunami on the northeast coast and how it resembled what was left of Hiroshima after the bombing.

A U.S. warplane dropped the atomic bomb, nicknamed "Little Boy", on this western city on Aug. 6, 1945 in the closing days of World War Two. The death toll by the end of the year was estimated at about 140,000 out of the total 350,000 that lived there at the time.

The United States dropped a second atomic bomb on the southern city of Nagasaki on Aug 9. Japan surrendered six days later.

LINES BLURRED

Japan has a self-imposed ban against nuclear arms, part of its pacifist post-war constitution.

But even many anti-nuclear groups have been careful not to draw parallels between what happened in Hiroshima and Nagasaki and dangers posed by the peacetime use of nuclear reactors.

Prior to the Fukushima crisis, nuclear energy accounted for nearly a third of Japan's energy supply. Hiroshima, an industrial city of 1.2 million, had also for decades relied on utility firm Chugoku Electric's Shimane nuclear power plant, 600 km (370 miles) west of Tokyo, for some of its electricity.

But since the March 11 quake and tsunami triggered radiation leaks at Tokyo Electric Power Co's Fukushima plant 240 km (150 miles) northeast of Tokyo, public sentiment has shifted.

"We hadn't thought so deeply about it until now. But I think it (nuclear plant) is not so different from the atomic bomb," said Michiko Kato, a 73-year-old survivor who lost her sister to the bomb.

"There is nothing made by human beings that is perfect... I don't want to use anything like this."

About a thousand protesters marched after the ceremony, holding banners saying "No more Fukushima, no more Hiroshima."

Unpopular Kan, who has said he will resign without clarifying when, has seized the shift in the public mood and is calling for an overhaul of Japan's energy policy. About 70 percent of voters back his vision, a recent poll showed.

But it remains unclear what will happen to his visions after he resigns. Support rating for Kan is under 20 percent and calls are growing among lawmakers and the public for him to quit soon.