Thousands of people near the Fukushima power plant in Japan are being evacuated after its cooling system failed following the earthquake.
The Japanese government has ordered the evacuation of nearly 3,000 people after declaring a state of emergency at the plant in Onahama city, about 170 miles north-east of Tokyo.
The nuclear safety agency said that workers at the power plant are trying to restore cooling water supply at the plant after the backup power generation system experienced a mechanical failure.
Tokyo Electric Power Company (TEPCO) said it has been trying to restore power to its emergency power system so that it can add water inside the reactors.
A spokesman added that it was working to maintain water levels to avert the exposure of nuclear fuel rods.
TEPCO was operating three out of six reactors at the nuclear plant at the time of the earthquake, all of which have since been shut down while the remaining three reactors had already been shut for planned maintenance.
Chief cabinet secretary Yukio Edano said that the evacuation was a precaution and that the plant was not in immediate danger of radiation leak.
The emergency was triggered by the largest earthquake to ever hit Japan, which struck the country at a depth of six miles about 80 miles off the eastern coast at magnitude 8.9.
This in turn caused a 10 metre tsunami that slammed into the eastern coast, with early reports saying that at least 60 people had been killed while 56 are missing.
Just hours later police reported finding two to three hundred bodies in Sendai city, the closest city to the epicentre. The death toll is likely to continue climbing given the scale of the disaster.
The Hawaii-based Pacific Tsunami Warning Centre has widened its alert beyond east Asia to include Hawaii, Australia, New Zealand, the entire US western coast, Mexico, Central and South America and the rest of the Pacific Ocean.
There have also been around 19 aftershocks in Japan at about magnitude 6.0, with dozens of cities and villages along a 1,300 miles stretch of coastline shaken by violent tremors that have reached as far away as Tokyo – 240 miles away from the earthquake epicentre.
"Our initial assessment indicates that there has already been enormous damage," Edano said. "We will make maximum relief effort based on that assessment."
Trouble has been reported at other nuclear power plants, with a fire breaking out at the turbine building of one of the Onagawa power plants in Miyagi, separate to the plant’s reactor.
It has since been extinguished and the cause is under investigation, according to Tohoku Electric Power Company.
While another plant at Onagawa is experiencing a water leak there have been no reports of radioactive leaks at these or any other nuclear plants in Japan.
The nuclear power sector in Japan produces about 30 per cent of the country's electricity and has been rocked periodically over the past decade by safety concerns.
Many reactors are located in earthquake-prone zones such as northeastern Fukushima prefecture and Fukui prefecture on the Japan seacoast.
Japan's worst previous quake was in 1923 in Kanto, an 8.3-magnitude shock that killed 143,000 people, according to US Geological Society. A 7.2-magnitude quake in Kobe city in 1996 killed 6,400 people.