Sri Lanka issued a tsunami warning, urging residents in coastal areas to evacuate immediately and travel at least a kilometre away towards high ground after an earthquake measuring 8.2 hit off the coast of Sumatra island in Indonesia.

The US Geological Survey said the quake measured 8.7.

The Sri Lankan meteorological department said the residents along the island's coastlines, which were battered in the December 26 tsunami, were asked to evacuate.

"We are not certain that there will be another tsunami, but we not taking any chances," Prime Minister Mahinda Rajapakse said. "We have alerted the police to help in the evacuation process."

State-run Rupavahini television network said people should move at least two km away from the east coast.

Police chief Chandra Fernando said security has been stepped up to ensure that there is no looting along the coastline.
    
Local residents along the north-western coastal area of Negombo said people moved to temples and churches.

Along the island's southern coastal district of Matara, local police urged coastal residents to move inland.