A 5.8-magnitude earthquake struck off Indonesia's Sumatra island, meteorologists said, but there were no immediate reports of casualties or damage.

The quake hit at 2:20 pm (0720 GMT) with the epicentre 139 kilometres (86 miles) southwest of Gunungsitoli city in North Sumatra province, 86 kilometres deep, the Indonesian Meteorological and Geophysics Agency said.

No tsunami warning was issued.

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