An earthquake with a magnitude of 7.3 struck off the west coast of Indonesia's Northern Sumatra on Wednesday, the US Geological Survey reported, but there were no immediate reports of casualties.
A tsunami warning was issued by the Pacific Tsunami Warning Center, and Indonesia also issued a tsunami warning but lifted it about two hours later.
The quake, which had a depth of 29 kilometres, hit at 2:37 am (1837 GMT) around 261 miles southwest of Banda Aceh, the capital of Aceh province on Indonesia's Sumatra island.
An official at Indonesia's Meteorology and Geophysics Agency said there were no immediate reports of casualties.
"The quake was in the sea and a tsunami warning is in force, but so far we have no reports of casualties or damage," Suharjono, the agency's technical chief, told AFP before the warning was lifted.
The agency initially reported a 7.6-magnitude quake, but later downgraded that to magnitude 7.1.
The Pacific Tsunami Warning Center said the threat of a widespread tsunami did not exist but added: "There is a very small possibility of a local tsunami that could affect coasts located usually no more than a hundred kilometres from the earthquake epicentre."
The Indonesian agency also reported two aftershocks of magnitude 5.4 and 5, respectively about 30 minutes and one hour after the initial quake.
In Banda Aceh, the ground shook for 30 seconds and terrified residents rushed out of their homes, but they returned indoors shortly after, an AFP reporter there said.
Some coastal residents had moved further inland, taking shelter in mosques or camped by the roadside as a precautionary measure, but there was no sense of panic, he said. The aftershocks were not felt in Banda Aceh, he added.
In December 2004, a giant 9.1-magnitude quake off the coast of Aceh province on the northern tip of Sumatra triggered a tsunami in the Indian Ocean that claimed 220,000 victims, with Indonesia accounting for three-quarters of the figure.