Some 10,000 people are missing in the port town of Minamisanriku in Miyagi prefecture.
The death toll has now surpassed that of the 1995 Kobe earthquake, which killed 6,434 people. Last week’s quake is now Japan's deadliest natural disaster since the 1923
Great Kanto Earthquake, which killed more than 142,000 people.
Japan deployed a fleet of fire engines to cool Fukushima nuclear plant Friday. Tonnes of water were used to douse overheating fuel rods at Number one power station, targeting the number three reactor.
The fuel rod pools at reactors three and four may be boiling and are not fully covered by roofs that would reduce radiation leaks.
The government and the plant’s operator Tepco have been criticised for not being completely candid in their announcements on what is going on at the plant.
“I can see why the Japanese wouldn’t want all the information to go out perhaps,” says correspondent Julian Ryall. “It might cause mass panic amongst the population and we do have a problem with fuel and they really don’t want the roads to be flooded with refugees.”
The earthquake and the tsunami shut down the plant's reactor cooling systems, sparking a series of explosions and fires. Authorities have since struggled to keep the fuel rods and fuel storage containment pools under water. If they are exposed to air, they could degrade further and emit large amounts of dangerous radioactive material.
On Thursday, helicopters dropped water onto the number three reactor.
"There is no doubt that water entered the pool, but we have not confirmed how much water is in there," said chief government spokesman Yukio Edano.
He put radiation levels Friday at about 100 microsieverts, and said there was no immediate threat to human health. A dose of 1,000 microsieverts causes temporary radiation sickness such as nausea.
Workers are making progress in restoring power lines, Edano said, in a bid to reactivate the plant's cooling systems.
"The power cable is near. We would like to speed up this operation as we can then use it to speed up the rest of what we have to do," Edano said.
Japan's nuclear safety agency on Friday raised the Fukushima crisis level to five from four on the international scale that goes up to seven. The French nuclear authority has rated the disaster at six. The 1986 Chernobyl explosion was level seven.