TOKYO - A strong earthquake hit Japan's southern island of Okinawa early on Saturday and Japan's weather agency issued a tsunami warning for up to 2-metres, but this was later lifted and there were no reports of major damage.

The U.S. Geological Survey said the 7.3 magnitude quake struck at 5:31 a.m. on Saturday (2031 GMT on Friday) 52 miles east of the island's capital of Naha, a city of about 320,000 about 1,600 km (1,000 miles) south of Tokyo.

The Japan Meteorological Agency, which put the magnitude at 6.9, warned residents near the coast to evacuate to high ground, but the tsunami warning was later lifted.

Okinawa prefectural police official Noritomi Kikuzato told Reuters there were no reports of injuries or major damage.

"First there was a strong vertical shake, then sideways. The strong quake lasted for about 10 seconds," said Naha city official Seiboku Sueyoshi.

An official at oil refiner Nansei Sekiyu KK said operations at its 100,000 barrels per day Nishihara refinery on the island were continuing normally after the quake and that there had been no reports of major damage to the facilities.

Public broadcaster NHK said local fire departments so far had no reports of injuries or damage to buildings.

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.

In October 2004, an earthquake with a magnitude of 6.8 struck the Niigata region in northern Japan, killing 65 people and injuring more than 3,000.

That was the deadliest quake since a magnitude 7.3 tremor hit the city of Kobe in 1995, killing more than 6,400.

(Reporting by Yoko Kubota, Chris Gallagher, Edwina Gibbs and Osamu Tsukimori; Writing by Linda Sieg; Editing by Charles Dick)