Tokyo - The biggest earthquake on record to hit Japan rocked its northeast coast on Friday, triggering a 10-metre tsunami that killed hundreds of people and swept away everything in its path.
Thousands of residents near a nuclear plant in Fukushima prefecture, north of Tokyo, were told to evacuate as a precaution after the 8.9 magnitude quake, but the government said no radiation was leaking.
Up to 300 bodies were found in the coastal city of Sendai, media said. NHK television said the victims appeared to have drowned. The extent of the destruction along a lengthy stretch of coastline suggested the death toll could rise significantly.
Tsunami warnings were issued across the Pacific but were later lifted for some of the most populated countries in the region, including Australia, Taiwan and New Zealand.
Other Japanese nuclear power plants and oil refineries were shut down and one refinery was ablaze. Television footage also showed an intense fire in the waterfront area near Sendai, the city hardest hit by the quake.
A major explosion hit a petrochemical complex in Miyagi prefecture after the quake, Kyodo said.
Political leaders pushed for an emergency budget to help fund relief efforts after Prime Minister Naoto Kan asked them to "save the country", Kyodo news agency reported.
Stunning TV footage showed a muddy torrent of water carrying cars and wrecked homes at high speed across farmland near Sendai, home to one million people and which lies 300 km (180 miles) northeast of Tokyo. Ships had been flung onto a harbour wharf, where they lay helplessly on their side.
The quake, the most powerful since Japan started keeping records 140 years ago, sparked at least 80 fires in cities and towns along the coast, Kyodo news agency said.
A ship carrying 100 people had been swept away by the tsunami, Kyodo said. One train was derailed and another unaccounted for.
In Tokyo, residents who had earlier fled swaying buildings jammed the streets trying to make their way home after much of the city's public transportation was halted.
Electronics giant Sony Corp, one of the country's biggest exporters, shut six factories, as air force jets raced to the northeast coast to determine the extent of the damage.
The Bank of Japan, which has been struggling to boost the anaemic economy, said it would do its utmost to ensure financial market stability as the yen and Japanese shares fell.
"I was unable stay on my feet because of the violent shaking. The aftershocks gave us no reprieve. Then the tsunamis came when we tried to run for cover. It was the strongest quake I experienced," a woman with a baby on her back told television.
The tsunami alerts revived memories of the giant waves which struck Asia in 2004. The Pacific Tsunami Warning Centre issued alerts for countries to the west and across the Pacific as far away as Colombia and Peru.
The earthquake was the fifth most powerful to hit the world in the past century.
There were several strong aftershocks. In Tokyo, there was widespread panic. An oil refinery near the city was on fire, with dozens of storage tanks under threat.
Around 4.4 million homes were without power in northern Japan, media said.
NHK television showed flames and black smoke billowing from a building in Odaiba, a Tokyo suburb, and bullet trains to the north of the country were halted. Thick smoke was also pouring out of an industrial area in Yokohama's Isogo area. TV showed residents of the city running out of shaking buildings, shielding their heads with their hands from falling masonry.
TV footage showed boats, cars and trucks tossed around like toys in the water after a small tsunami hit the town of Kamaichi in northern Japan. An overpass, location unknown, appeared to have collapsed and cars were turning around and speeding away.
"The building shook for what seemed a long time and many people in the newsroom grabbed their helmets and some got under their desks," Reuters correspondent Linda Sieg said in Tokyo. "It was probably the worst I have felt since I came to Japan more than 20 years ago."
The US navy said its ships had been unaffected by the tsunami and were ready to provide disaster relief if needed. China offered to provide earthquake relief.
The quake struck just before the Tokyo stock market closed, pushing the Nikkei down to end at a five-week low. Nikkei futures trading in Osaka tumbled as much as 4.7% in reaction to the news.
The disaster also weighed on markets elsewhere.Great Kanto quake
The quake surpasses the Great Kanto quake of September 1, 1923, which had a magnitude of 7.9 and killed more than 140 000 people in the Tokyo area.
The 1995 Kobe quake caused $100bn in damage and was the most expensive natural disaster in history. Economic damage from the 2004 Indian Ocean tsunami was estimated at about $10bn.
Passengers on a subway line in Tokyo screamed and grabbed other passengers' hands during the quake. The shaking was so bad it was hard to stay standing, said Reuters reporter Mariko Katsumura.
Japan's northeast Pacific coast, called Sanriku, has suffered from quakes and tsunamis in the past and a 7.2 quake struck on Wednesday. In 1933, a magnitude 8.1 quake in the area killed more than 3 000 people.
Earthquakes are common in Japan, one of the world's most seismically active areas. The country accounts for about 20 percent of the world's earthquakes of magnitude 6 or greater.