Tokyo: A ferocious tsunami spawned by one of the largest earthquakes ever recorded slammed Japan's eastern coast on Friday, killing hundreds of people as it swept away boats, cars and homes while widespread fires burned out of control.

Tsunami warnings blanketed the entire Pacific, as far away as South America, Canada, Alaska and the entire U.S. West Coast.

Police said 200 to 300 bodies have been found in the northeastern coastal city of Sendai. Police said another 88 were confirmed killed and 349 were missing.

The death toll was likely to continue climbing given the scale of the disaster.

The magnitude 8.9 offshore quake unleashed a 23-foot (7-meter) tsunami and was followed by more than 50 aftershocks for hours, many of them of more than magnitude 6.0.

The government ordered thousands of residents near a nuclear power plant in Onahama city to evacuate because the plant's system was unable to cool the reactor. The reactor was not leaking radiation but its core remained hot even after a shutdown.
The plant is 170 miles (270 kilometers) northeast of Tokyo.

Dozens of cities and villages along a 1,300-mile (2,100-kilometer) stretch of coastline were shaken by violent tremors that reached as far away as Tokyo, hundreds of miles (kilometers) from the epicenter.

"The earthquake has caused major damage in broad areas in northern Japan," Prime Minister Naoto Kan said at a news conference.

In the capital Tokyo, where millions evacuated strongly swaying buildings, multiple injuries were reported when the roof of a hall collapsed during a graduation ceremony, police said.

Plumes of smoke rose from at least 10 locations in the city, where four million homes suffered power outages. An oil refinery was ablaze near Tokyo.

The Pacific Tsunami Warning Centre issued a widespread warning for territories as far away as South America, New Zealand and Hawaii, where people were ordered to evacuate coastal areas.

The Red Cross warned that if the tsunami were to reach between four and 10 metres it would swamp some of the islands in its path. But countries in the tsunami's path reported only minor waves.

The tsunami also reached Sendai airport, submerging the runway while a process known as liquefaction, caused by the intense shaking of the tremor, turned parts of the ground to liquid.

The government said it was operating on an atomic power emergency footing after a fire broke out in the turbine building of a nuclear plant in Onagawa but said no radiation leaks were detected among its reactors.

The first quake struck just under 400 kilometres (250 miles) northeast of Tokyo, the US Geological Survey said. It was followed by more than 40 aftershocks, one as strong as 7.1.

"We were shaken so strongly for a while that we needed to hold on to something in order not to fall," said an official at the local government of the hardest-hit city of Kurihara in Miyagi prefecture.

"We couldn't escape the building immediately because the tremors continued... City officials are now outside, collecting information on damage," she told AFP by telephone.

A major blackout occurred across a wide area of northeastern Japan.

Prime Minister Naoto Kan quickly assembled his cabinet after the quake hit, and the government dispatched naval vessels from near Tokyo to Miyagi.

US President Barack Obama led international offers of sympathy and aid in what he called Japan's 'time of great trial', while the Kan government called on help from US forces stationed in the country.

The quake affected Japan's key transportation systems, including Narita airport, which shut its runways for safety checks to leave 10,000 passengers stranded, before reopening for departing flights only.

The quake, which hit at 14:46 pm (0546 GMT) and lasted about two minutes, rattled buildings in greater Tokyo, the world's largest urban area and home to some 30 million people.

In Tokyo, where the subway system stopped, sirens wailed and people streamed out of buildings.

The quake sent the Nikkei share index plunging at the close while the yen fell sharply against the US dollar before recovering. Stocks in European re-insurers, which cover against major natural disasters, also dived.

Japan sits on the "Pacific Ring of Fire", which is dotted with volcanoes, and Tokyo is in one of its most dangerous areas where three continental plates are slowly grinding against each other, building up enormous seismic pressure.

The government's Earthquake Research Committee has warned of a 70 percent chance that a great, magnitude-eight quake will strike within the next 30 years in the Kanto plains, home to Tokyo's vast urban sprawl.

The last time a "Big One" hit Tokyo was in 1923, when the Great Kanto Earthquake claimed more than 140,000 lives, many of them in fires. In 1855, the Ansei Edo quake also devastated the city.

In 1995 the Kobe earthquake killed more than 6,400 people.

More than 220,000 people were killed when a 9.1-magnitude quake hit off Indonesia in 2004, unleashing a massive tsunami that devastated coastlines in countries around the Indian Ocean as far away as Africa.

However, small quakes are felt every day somewhere in Japan and people take part in regular drills at schools and workplaces to prepare for a calamity.

Nuclear power plants and bullet trains are designed to automatically shut down when the earth rumbles and many buildings have been quake-proofed with steel and ferro-concrete at great cost in recent decades.