More than 12,000 people took refuge in evacuation centres in northwest Japan on Tuesday after an earthquake the previous day flattened homes, killing nine people and injuring more than 1,000, and triggered a leak of contaminated water from a nuclear plant.

As aftershocks continued, forecasts for wet weather raised fears of mudslides that could add to the devastation.

Water, gas and electricity supplies were cut by the 6.8 magnitude quake that hit Niigata prefecture on Monday morning, also causing a radiation leak and fire at the world's biggest nuclear plant.

"I'm worried because I don't know how long this is going to continue. What we need is electricity, water and gas back," said Ichiro Yoneyama, 66, a boat instructor who visited an evacuation centre with his young grandchildren to get food. "Neighbours are helping one another, but there's only so much we can do."

Nine elderly people were killed and one person was missing, a Niigata prefecture official said.

A small fire and a leak of 1,200 litres (317 U.S. gallons) of water containing radioactive materials at Tokyo Electric Power Co.'s (TEPCO) Kashiwazaki-Kariwa nuclear power plant -- the world's largest -- reignited fears about nuclear safety in a country reliant on atomic power for one-third of its electricity.

With 342 houses destroyed and about 430 damaged in Niigata prefecture alone, according to officials, it was unclear when people could go home. Worries were mounting about the health of evacuees, many of whom are elderly.

"The damage was worse than anticipated," Kashiwazaki Mayor Hiroshi Kaeda told reporters. "If we can restore water services more people can go home, so that's what we want to do first."

Streets in Kashiwazaki were lined with damaged or collapsed houses, mostly wooden structures with heavy tile roofs, and many roads were blocked because of cracks, causing traffic jams.

Some people worked on repairs, covering damaged roofs with blue plastic sheets, others picked through scattered rubble. Across the street from one evacuation centre was a temple building crushed by the quake and a cemetery with fallen stone lanterns.

RICE BALLS AND WATER

Residents lined up holding plastic bottles for fresh water, which was trucked in by local officials and a contingent of about 500 members of the armed forces.

The navy shipped in emergency rations and helmeted soldiers in camouflage uniforms made rice balls to hand out at evacuation centres, where crowds huddled sitting on "tatami" straw mats with blankets and a few belongings.