Thousands of anti-nuclear demonstrators rallied in Tokyo Saturday ahead of the second anniversary of the March 11 earthquake and tsunami disaster, urging Japan's new government to abandon nuclear power.

The gathering of some 15,000 people, according to organisers, at a park in central Tokyo drew disaster victims and celebrities, including Nobel laureate writer Kenzaburo Oe, before the anniversary Monday of the disaster that killed 19,000 and sparked reactor meltdowns at the Fukushima Daiichi nuclear plant.

Protesters marched through the capital later in the day and issued a statement calling on Prime Minister Shinzo Abe, who took office late December following his party's election win, to dismantle all nuclear plants.

Abe, whose conservative Liberal Democratic Party has close ties with the nation's powerful business circle, has repeatedly said he would allow reactor restarts if their safety could be ensured.

"The new administration should not misunderstand that the (election) victory can mean approval of policies to maintain nuclear power," the statement said.

"We will request policies to swiftly begin procedures in decommissioning nuclear reactors and disapprove any plans to newly build nuclear plants," it said.

Japan turned off its stable 50 reactors in the wake of the disaster on March 11, 2011, but restarted two of them citing possible summertime power shortages.

Radiation from the plant, some 220 kilometres (140 miles) northeast of Tokyo, has been spread over a large area in the worst nuclear accident since the 1986 Chernobyl disaster.