Jakarta  - An undersea earthquake measuring 6.4 on the Richter scale struck off the eastern Indonesian island of Sumba late Monday afternoon, but there were no immediate reports of injury and damage, meteorologists said.

The quake hit at a depth of 86 kilometres with its epicentre about 107 kilometres north-west of Waingapu, a district town on Sumba island in Indonesia's East Nusa Tenggara province. It occurred at 6:52 pm (1052 GMT), the Indonesian Meteorology and Geophysics Agency said.

There were no immediate reports of injury or structural damage from the quake, meteorologists said.

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.(dpa)