TOKYO (AFP) - Thousands of campaigners rallied against nuclear power in Tokyo on Saturday, as the government and utilities move towards resumption of reactors in southern Japan.

More than 5,000 protesters gathered at Hibiya Park in downtown Tokyo to urge the government not to restart nuclear plants, as regulators review whether to let Kyushu Electric Power to restart two reactors at its Sendai power plant.

"Japan is prone to earthquakes. We have to seriously think about whether nuclear power is a good idea for Japan," said Mr Masatoshi Harada, 60, as he joined fellow protesters at the park and later to march toward the Ginza shopping district.

"This is an opportunity for Japan to drop nuclear power," he said.

Last week tens of thousands held a rally at the same site to voice fears about any reliance on nuclear power.

Saturday's event came days after Japan marked the third anniversary of a 9.0-magnitude earthquake that struck northern Japan in March 11, 2011.

The quake prompted killer tsunami along the northern Pacific coastline.

The twin disasters killed 15,884 people and left 2,633 people still unaccounted for.

Huge waves swamped cooling systems of the Fukushima plant, which went through reactor meltdowns and explosions that spewed radioactive materials to the vast farm region.

No one died as a direct result of the atomic accident, but at least 1,656 people died as a result of complications related to stress and other conditions while their lives in evacuation become extended.

Supporters of nuclear power, including Prime Minister Shinzo Abe, say Japan needs atomic energy to ensure the economic health of the world third largest economy.

But protesters argued that Japan can live without nuclear power as it has done so for many months.

All of the nation's roughly 50 commercial nuclear reactors have remained offline due to tense public opposition to restarting them.

"Nuclear plants have been closed, so you cannot say we cannot live without nuclear energy," anti-nuclear campaigner Junichi Okano said.