PADANG, Indonesia: A strong 6.2-magnitude earthquake struck off the coast of western Indonesia early Friday, US seismologists said, but no tsunami warning was issued and there were no immediate reports of casualties or damage.

The quake hit the Mentawai islands in West Sumatra province about 75 kilometres (46 miles) southwest of the provincial capital Padang at 00:06 am (1706 GMT), at a depth of 49 kilometres, according to the US Geological Survey.

The disaster agency said officials were checking for damage and casualties.

John Nedy, a resident of Padang, said people fled their homes when the quake struck, and most were reluctant to return for the time being.

"The earth quake was very strong. Some people say it´s safe now to go back to our homes, but most people are still afraid," Nedy told AFP.

Indonesia experiences frequent seismic and volcanic activity due to its position on the Pacific "Ring of Fire", where tectonic plates collide.

An earthquake struck the country´s western Aceh province in December 2016, killing more than 100 people, injuring many more and leaving tens of thousands homeless.