A major 7.1-magnitude earthquake shook eastern Indonesia's Maluku islands today but there was no tsunami alert, the US Geological Survey said.

The quake hit at 1653 GMT some 365 kilometres south-southeast of Ambon in the Maluku islands at a relatively deep 157 kilometres, it said, revising its strength down slightly from an initial measurement of 7.2.

Indonesian government seismologists put it at 7.4 but said it would not trigger a tsunami because its epicentre was so deep in the Banda Sea.

"We have not received any damage report so far," Suhardjono, head of the quake and tsunami unit at the Indonesian Meteorology, Climatology and Geophysics Agency, told AFP.

The quake was felt only weakly in the districts of North Halamahera and Morotai which were closest to the epicentre, the National Disaster Mitigation Agency said in an update.

Indonesia sits on the Pacific "Ring of Fire" where continental plates collide, causing frequent seismic and volcanic activity.