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JAKARTA, Sept 26 (Reuters) - A strong earthquake hit off the coast of Indonesia's Sumatra island, seismologists said on Wednesday.

The U.S. Geological Survey said the quake measured 6.4.

Indonesia's meteorological agency said it struck 149 km (93 miles) southwest of Painan in West Sumatra province and was at a depth of 70 km.

More than 20 people were killed when an 8.4 magnitude earthquake hit western Sumatra on Sept. 12, and thousands of homes were damaged or destroyed in the area.

In the past two weeks, the area has been hit by a series of quakes and strong aftershocks, setting off tsunami warnings in Indonesia and other countries in the region.

Indonesia, which is situated in a belt of intense seismic activity known as the "Pacific Ring of Fire", was hit by a huge earthquake in December 2004, triggering a devastating tsunami in the Indian Ocean, which killed more than 230,000 people in the region, including 170,000 Indonesians.

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