A powerful earthquake struck north-eastern Japan and the greater Tokyo area Monday, prompting warnings that a tsunami up to 5 metres high was heading toward the coast, dpa reported.
Shortly after the magnitude-6.2 tremor, an explosion was heard at a nuclear plant in Fukushima, 240 kilometres north of Tokyo, where cooling systems at reactors have failed since Friday's magnitude-9 earthquake and tsunami.
The public broadcaster NHK showed footage of a black cloud of smoke rising over reactor number 3 in Fukushima. Technicians had been working for days there to reduce pressure and prevent a meltdown at the reactor.
It was unclear whether the inner containment hull of the reactor had been damaged.
Monday's aftershock at 10:02 (0102 GMT) violently shook buildings in Tokyo and was felt upon news from the Kyodo News agency that 1,000 bodies had been found on the shore of north- eastern Japan.
The bodies were found on Ojika Peninsula in Miyagi prefecture, one of the areas hit hardest by Friday's quake and tsunami.