Fukushima nuclear workers and their supporters shouts slogans as they raise their fists in front of the headquarters of Tokyo Electric Power Company (TEPCO), operator of the tsunami-battered Fukushima Daiichi nuclear power plant, during a rally in Tokyo on March 14, 2014. Toru Yamanaka/AFP/Getty Images

Thousands of people in Tokyo have rallied against nuclear power as the government and utilities prepare to restart reactors in southern Japan.

More than 5,000 protesters gathered at Hibiya Park in Tokyo on Saturday to pressure the government not to restart the country's nuclear power stations.

"Japan is prone to earthquakes. We have to seriously think about whether nuclear power is a good idea for Japan," said protester Masatoshi Harada. "This is an opportunity for Japan to drop nuclear power."

Regulators are currently reviewing whether to let Kyushu Electric Power restart two reactors at its Sendai power plant.

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

The earthquake prompted a deadly tsunami along the northern Pacific coastline and huge waves swamped already damaged cooling systems at the Fukushima Daiichi Nuclear Power Plant, resulting in three reactor meltdowns and explosions that spewed radioactive materials into the vast, rural region.

The wrecked plant, which continues to vent radionuclides into the atmosphere and leak tens of thousands of gallons of contaminated water into the Pacific Ocean, is expected to take at least 40 years to stabilize. The surrounding area will show high levels of radioactive contamination for decades to come.

On Friday, nearly 100 workers who helped to clean up the crippled plant rallied outside the headquarters of Fukushima operator Tokyo Electric Power Company (TEPCO), complaining they were forced to work for meager pay in dangerous conditions

Workers also rallied outside Maeda Corp Friday, one of the contractors hired to clean up the plant and surrounding areas.

The earthquake and tsunami killed 15,884 people and left 2,633 people still missing.

Supporters of nuclear power, including the prime minister, Shinzo Abe, said Japan needs atomic energy to ensure the economic health of the world's third largest economy.

But protesters at Saturday's demonstration argued that the country can live without nuclear power as it has done for most of the last 36 months.

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

All of the nation's roughly 50 commercial nuclear reactors have gradually been shut down since 2011 and remain offline due to unprecedented public opposition to restarting them.