A strong earthquake, registering a preliminary magnitude of 6.6 at the Richter scale, shook Japan's southernmost prefecture of Okinawa early Friday afternoon, the Japan Meteorological Agency said.

The focus of the quake is near Yonakuni Island, one of a numberof small islands making up Okinawa Prefecture.

The agency did not issue any tidal wave warnings.

The quake, which occurred around 1:09 p.m. (0409 GMT), marked lower 5 on the Japanese seismic intensity scale of 7 on Yonakuni, and 4 on Ishigaki and Iriomote Island.

Source: Xinhua