TOKYO, March 14, 2012 (AFP) - A minor tsunami hit Japan's northeastern coastline Wednesday, NHK television reported, after a strong earthquake rocked the region nearly a year on from Japan's worst post-war natural disaster.

The 10-centimetre (four inch) wave and 6.8 magnitude quake, which struck some 210 kilometres (130 miles) off the northern island of Hokkaido, prompted local authorities to issue an evacuation warning for coastal residents.

Japan's meteorological agency had initially said the tsunami could be as high as 50 centimetres, but US monitors said there was no Pacific-wide tsunami threat.

The warning comes after a 9.0-magnitude earthquake triggered a monster tsunami on March 11 last year that killed more than 19,000 people and crippled Japan's Fukushima nuclear plant, sparking the world's worst atomic accident in a generation.

There were no reports of damage at nuclear facilities in the area affected by Wednesday's 6.8 quake, the Kyodo news agency said.

The meteorological agency also warned the tsunami could reach the Kuril islands, off Hokkaido, which Russia has controlled since Japan's surrender at the end of World War II.

On Sunday, Japan fell silent to remember last year's tragedy with tearful families gathering in towns and villages across the country's shattered northeast to remember those they lost as the towering waves smashed ashore.

Tens of thousands were forced to evacuate from a 20-kilometre exclusion zone immediately around the Fukushima plant, while many families with small children moved away from the prefecture completely.

On Sunday's anniversary, thousands protested against nuclear power in demonstrations held across the world.

Japan has temporarily shut most of its 54 commercial nuclear reactors.