JAKARTA - A MODERATE earthquake struck off the coast of Indonesia's Sumatra island on Friday, seismologists said, but there were no immediate reports of damage.

The US Geological Survey said a 5.0-magnitude quake struck at 11.50pm (1650 GMT, 12.50am Singapore time) on Friday, at a depth of 35km and was centred 234km south-south-west of Sumatra's Sibolga, around the Batu Islands.

No tsunami alert was issued.

Indonesia sits on the Pacific 'Ring of Fire,' where the meeting of continental plates causes high volcanic and seismic activity. -- AFP