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More than 1,000 people were feared dead after Japan's strongest earthquake on record triggered a destructive tsunami, the government said Saturday as it expressed concerns over possible radiation leaks from damaged nuclear reactors, DPA reported.
Japan was assessing the damage from Friday's 8.9-magnitude quake and devastating tsunami that rocked the north-eastern part of the country, even as aftershocks continued to hit.
The death toll would probably be well over 1,000, said Yukio Edano, chief cabinet secretary.
Authorities had recovered hundreds of bodies, with more than 1,000 people still missing and many injured, news reports said.
The government feared more large-scale aftershocks could add to the destruction, as the Meteorological Agency issued further tsunami warnings for many coastal regions in the country.
The agency said more than 100 aftershocks had occurred, many of them stronger than magnitude-6 on the Richter scale.
The Nikkei business daily said some 210,000 people had been evacuated in north-eastern Japan, while thousands were stranded in Miyagi, waiting for assistance, public broadcaster NHK said.
Rescuers searched for survivors amid collapsed buildings in many flooded cities. Some victims were airlifted by the military.
Troops and other rescue teams were being rushed to north-eastern parts of the country, officials said.
International assistance was on its way, as the United States dispatched more than 140 personnel on Friday, and New Zealand said Saturday it would send a 48-member search-and-rescue team.
The Japanese government had mobilised 50,000 search and rescue workers, and sent 190 aircraft and 25 vessels to areas affected by the quake and tsunami.
Officials were working with the US military stationed in Japan to transport about 900 Japanese troops and 250 vehicles by US ships.
Thousands of houses were destroyed, several bridges collapsed, bus and train services were shut down and many roads were closed. Mobile phone networks and landline services were affected.
Television footage showed flattened fishing villages and shattered cities with piles of rubble on the streets as the tsunami surged 5 kilometres inland in some areas, forcing many to spend the night on the roofs of their houses as temperature dropped to freezing point.
In the city of Rikuzen Takata, one of the worst-hit areas, of the 8,000 houses, some 5,000 were destroyed, news reports said.
The devastating scenes were "similar to what I saw off Sumatra," Minoru Watanabe, a Tokyo-based town planning expert, told TBS television, referring to the powerful earthquake and tsunami that hit Indonesia in December 2004 that caused more than 200,000 deaths.
Around 1,800 houses in Minami Soma, Fukushima Prefecture were destroyed, with relief efforts limited to helicopters, as further tsunamis were feared.
Radioactive caesium has been found near the nuclear power plants of Fukushima in the quake-stricken north-eastern region, the government's nuclear safety commission said.
But public broadcaster NHK reported as the amount of the leak is limited and most of radiation is still in the reactor, that is not a cause of concern, citing Naoto Sekimura, professor at the University of Tokyo, an expert of quantum engineering.
Evacuations had been ordered early Saturday after the cooling system at a second nuclear power plant broke down in the wake of the massive earthquake.
Residents within 3 kilometres of the Fukushima II power plant were ordered to leave their homes. Earlier in the day, authorities extended evacuations to residents living within 10 kilometres of another nearby nuclear plant, Fukushima I, where the cooling system experienced troubles Friday.
Radiation measurements inside the Fukushima I nuclear plant were 1,000 times higher than normal, the Kyodo news agency reported early Saturday, citing Japan's nuclear safety agency.
The country was facing the risk of blackouts as a result of damage to power systems caused by the earthquake and tsunami, the Tokyo Electric Power Co (TEPCO) warned Saturday.
The risk of power failures was not confined to the affected areas.
TEPCO urged businesses and residents to use electricity sparingly. The utility could currently provide only 37 million kilowatts of power, which could be increased by 1 million kilowatts by the evening.
The company has sought support from other operators, the Kyodo news agency reported.
TEPCO supplies power to the damaged Fukushima I nuclear plant. Ventilators at the plant had to be opened to release pressure within reactors. A small amount of radiation was released in the process, the company said.