Jakarta: A powerful quake struck near Indonesia's Sumatra island on Wednesday, the United States Geological Survey said, and the shock was felt across southeast Asia.

The USGS initially said on its Web site there was quake measuring 8.0, and then a short time later said there was a quake measuring 7.9 at slightly different location. It was unclear if there were two quakes.

The quake had the potential to cause a tsunami, an Indonesian meteorological agency official said.

India's government also issued a tsunami alert for the Andaman Islands, and Malaysia issued a warning to stay away from beaches.

Some offices in Jakarta were evacuated after the tremors were felt. Witnesses in Singapore and Thailand said they also felt the quake.

Indonesia suffers frequent earthquakes, lying on an active seismic belt on part of the so-called Pacific "Ring of Fire".