Japan has issued a tsunami warning for a group of islands south of Tokyo following a strong earthquake off Japan's eastern coast on Wednesday.

The quake measuring 6.8 on the Richter scale struck at around 3:11 p.m. (0611 GMT) about 200 km off the coast of Chiba prefecture.It was centered about 10 km below the ocean floor, the Meteorological Agency said.

Tsunami around 50 cm (20 inches) high were expected to hit the Izu islands around 3:30 p.m. (0630 GMT), it said.

There were no immediate reports of damage or casualty, but local residents near the shore were called to evacuate, public broadcaster NHK said.

Earthquakes are common in Japan, one of the world's most seismically active areas.

An earthquake measuring 6.8 on the Richter scale hit the Niigata region in northern Japan in October 2004, killing 40 people and injuring more than 3,000.

A magnitude 7.3 quake struck the city of Kobe on Jan. 17, 1995,killing more than 6,400.

It was in Kobe where the United Nations World Conference on Disaster Reduction opened Tuesday with the recent Indian Ocean tsunami disaster standing as a hot item at the meeting.

The conference observed a moment of silence for the victims of Indian Ocean tsunami.

At the five-day conference, more than 4,000 participants are expected to work out a program of action for the next 10 years, containing strategic goals and priorities, to realize the substantial reduction of disaster losses in lives and in the social, economic and environmental assets of communities and countries.

Source: Xinhua