TOKYO, March 12: An explosion at a nuclear power plant on Japan’s coast destroyed a building on Saturday and added leaking radiation, or even outright meltdown, to the threats menacing a nation just beginning to grasp the scale of a catastrophic earthquake and tsunami.

The Japanese government said radiation emanating from the plant appeared to have decreased after the blast, which produced an intensifying cloud of white smoke that swallowed the complex. But authorities did not say why, and the precise cause of the explosion and the extent of the ongoing danger were not clear.

Japan dealt with the nuclear threat as it struggled to determine the scope of the earthquake, the most powerful in its recorded history, and the tsunami that ravaged its northeast with breathtaking speed and power. The official count of the dead was 574, but the government said the figure could far exceed 1,000.

Teams searched for the missing along hundreds of miles of the Japanese coast, and thousands of hungry survivors huddled in darkened emergency centres that were cut off from rescuers and aid. At least a million households had gone without water since the quake struck. Large areas of the countryside were surrounded by water and unreachable.

The explosion at the nuclear plant, Fukushima Dai-ichi, 170 miles northeast of Tokyo, appeared to be a consequence of steps taken to prevent a meltdown after the quake and tsunami knocked out power to the plant, crippling the system used to cool fuel rods there.

The blast destroyed the building housing the reactor, but not the reactor itself, which is enveloped by stainless steel six inches thick. —AP