Jakarta, July 27 (DPA) An undersea earthquake registering 6.1 on the Richter scale struck Monday morning on the western coast of the Indonesian island of Sumatra, but there were no immediate reports of injury or damage, the Indonesian seismologist agency said.

The quake struck at 6.10 a.m. and was centred in the Indian Ocean, 73 km southwest of Bintuhan in Bengkulu province, Indonesia's National Meteorology and Geophysics Agency said.

The event occurred 57 km beneath the seabed.

There were no immediate reports of structural damage or injury.

Indonesia, the world's largest archipelago nation, sits atop the Pacific Ocean's Ring of Fire, where the meeting of continental plates causes high volcanic and seismic activity.