A major earthquake has struck off the coast of western Sumatra, Indonesian officials say.

The 7.5 magnitude quake near the Mentawi Islands at a depth of 14km (8 miles) triggered a tsunami watch, but officials later gave the all clear.

Indonesia's Meteorology and Geophysics Agency said the quake struck at 2142 (1442 GMT) and was felt in towns in Bengkulu and west Sumatra provinces.

There have so far been no reports of damage or casualties.

Initial reports put the depth of the quake at 33km (20.5 miles), but this was later revised by the US Geological Survey.

The shallow depth of the earthquake prompted the US-based Pacific Tsunami Warning Center to issue a "watch" bulletin.

"There was shaking that went on for about three seconds or so," Indonesian disaster management agency spokesman Priyadi Kardono told AFP news agency.

"Residents panicked and ran to the hills but now they are starting to come down. There is no report of casualties or damage."

Indonesia is regularly affected by earthquakes.

More than 1,000 people were killed by an earthquake off Sumatra in September 2009.

In June at least three powerful earthquakes struck the region, bringing down homes and leaving three people dead.

In December 2004, a 9.1-magnitude quake off the coast of Aceh triggered a tsunami in the Indian Ocean that killed a quarter of a million people in 13 countries including Indonesia, Sri Lanka, India and Thailand.

Indonesia sits on the Pacific "Ring of Fire", one of the world's most active areas for earthquakes and volcanoes.