JAKARTA - A 6.5-magnitude quake struck late Friday off the coast of Sumatra in Indonesia, seismologists said, but no tsunami alert was issued and there were no reports of damage or injuries.

The quake's epicentre was at a depth of 22 kilometres, the US Geological Survey said, and was 165 kilometres west of Bengkulu on Sumatra island.

The earthquake hit at 11:06 pm, waking people up, an AFP reporter said, but otherwise the effects were minimal.

The Hawaii-based Pacific Tsunami Warning Center did not issue an alert and said there was only a very small possibility of a local tsunami.

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

A 7.6-magnitude quake that struck Sumatra island in September killed more than 1,000 people.