A strong earthquake with a preliminary magnitude of 6.8 jolted near Ishigaki Island in Japan' s southernmost Okinawa Prefecture on Monday, said the Japan Meteorological Agency.

There were no reports of casualties or damage to properties.

The focus of the quake, which occurred at 9:06 a.m. (0006 GMT), was located some 10 km under the sea off Ishigaki Island, said the agency.

The agency issued a tsunami alert for Miyako Island and neighboring islands in Okinawa Prefecture and lifted the warning at 10 a.m.

The government set up a liaison office at the prime minister's office following the occurrence of the quake.

(Xinhua News Agency August 17, 2009)