A series of earthquakes struck eastern and western Indonesia in a span of several hours on Friday night-Saturday morning, the U.S. Geological Survey (USGS) reported on its website.

The strongest, 6.6-magnitude tremor was registered at 01:16 GMT on Saturday near the north coast of Papua at a depth of 29.8 km (18.5 miles). It was followed ten minutes later by a 5.6-magnitude quake in the same location at a depth of 27.6 km (17.2 miles).

Four consecutive moderate quakes, ranging from 5.2 to 5.7 magnitude, hit off the west coast of northern Sumatra late on Friday.

There have been no reports of damage or casualties, and no tsunami warning has been issued so far.

Part of the Pacific's Ring of Fire, Indonesia is in the world's most seismically active region, registering 6,000-7,000 earthquakes with a magnitude of 4.0 or above annually.

In December 2004, a 9.0-magnitude earthquake off the coast of Sumatra triggered a giant tsunami that killed at least 230,000 people across South East Asia, the majority in Indonesia's Aceh province.