More than two hours after the quake there were no reports of a tsunami from ocean rim countries or of any casualties from the tremor.

The Andaman Islands were badly hit by the 2004 Asian tsunami which was triggered by an earthquake off the Indonesian island of Sumatra and sent giant waves crashing into countries around the Indian Ocean.

The 2004 tsunami killed more than 220,000 people, most of them in the northern Indonesian province of Aceh.

Thousands of people were also killed in Sri Lanka, Thailand and India.

Japan quake

Another earthquake, with a preliminary magnitude of 6.6, jolted eastern and central Japan early on Tuesday.

The focus of the tremor was 20km below the surface of Suruga Bay in Shizuoka prefecture, around 150km southwest of Tokyo, the Japan Meteorological Agency said.

The government's Nuclear and Industrial Safety Agency said Chubu Electric Power Co Inc had halted all operations at its Hamaoka nuclear plant for safety checks.

Trains in the area were halted for safety checks and some highways were closed for damage inspections.

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

The country accounts for about 20 percent of the world's earthquakes of magnitude 6 or greater.