A strong earthquake jolted northeastern Japan on Sunday, and workers at the crippled Fukushima nuclear power plant were evacuated after an alert for a tsunami of 50 cm was issued by the country's metreological agency.

The US Geological Survey said the quake had a magnitude of 7.3.

There were no immediate reports of injuries or damage, public broadcaster NHK said. The area was hit by a massive earthquake and tsunami in March which destroyed the Fukushima power plant and triggered a radiation crisis.

Source: Agencies