An earthquake measuring 5.9 on the Richter scale rocked Ryukyu Islands at 11:11 PM Tuesday (0311 GMT Monday), the Hong Kong Observatory reported.

The epicenter was initially determined to be 27.3 degrees north latitude and 126.8 degrees east longitude, about 150 kilometers northwest of Naha, Japan.

China Seismological Monitoring Network (CSMN) reported slightly different data, saying that the earthquake measured 6.0 on the Richter scale at 11:07 PM, with its epicenter at 27.4 degrees north and 126.7 degrees east.

There was no immediate report of casualties or damage.

(Xinhua News Agency August 1, 2007)