Japanese Prime Minister Naoto Kan on Tuesday urged the population to remain calm in the face of an escalating crisis at a damaged north-eastern nuclear power plant.
He warned that further radiation leaks were possible at the plant in Fukushima.
Early Tuesday, a blast occurred at reactor 2 of the plant, and the operator Tokyo Electric Power Co said it feared the reactor containment vessel had been damaged. There were also reports about a fire at the building housing reactor number 4.
Mr. Kan said people still remaining within 20 km of the stricken plant must evacuate, the Kyodo News agency reported.