A 7.8 magnitude earthquake has struck off the coast of western Indonesia, the US Geological Survey (USGS) reports.
There have been no immediate reports of damage.
The USGS said the earthquake struck at 19:49 local time (12:49 GMT). It said the epicentre was 805km (500 miles) south-west of the city of Padang, and 24km deep.
Indonesian officials issued a tsunami warning for the regions of West Sumatra, North Sumatra and Aceh.
Australia also issued a tsunami warning for Cocos Island and Christmas Island in the Pacific. It also issued a tsunami watch for Western Australia but this was later lifted.
Australia’s Bureau of Meteorology said evacuations were not required on the islands but advised people to “get out of the water and move away from the immediate water’s edge”, because of the risk of dangerous waves and currents.
Authorities in India said their initial assessment was that there was no tsunami threat. Sri Lankan media also reported the country’s disaster management centre as saying there was no threat.
The earthquake was felt strongly in Padang for a few seconds, AFP reports, with people running out of their homes to higher ground.
Traffic ground to a halt and there was a sense of panic on the streets.
In 2004, an 8.9 magnitude earthquake triggered the world’s deadliest ever tsunami, killing more than 200,000 people.
After that disaster, a more effective tsunami monitoring system was put in place. Warnings are now issued more frequently after earthquakes in the area.
Indonesia lies on the Pacific “Ring of Fire” of plate boundaries, which produces high levels of seismic activity, including frequent earthquakes.
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