Jakarta: A strong earthquake hit late Monday off the western coast of Indonesia's Sumatra island, but no damage or casualties were immediately reported.

The 7.5-magnitude temblor struck at a depth of 9 miles (15 kilometres) on a small island off Sumatra, the US Geological Survey said. A massive earthquake and tsunami struck off the same island in 2004.

It was reportedly felt in five towns in Bengkulu and West Sumatra provinces, but so far there no reports of damages or casualties, said Tatok Yatimantoro of Indonesia's Meteorology and Geophysics Agency.

The tremor that struck at 9:42 pm (1642 GMT) was centered about 78 kilometres (48 miles) southwest of the Pagai Selatan in Mentawai Island, with a depth of 10 kilometres (6 miles), according to the Indonesian agency.

A tsunami watch for local areas was issued but lifted within an hour.

The world's largest archipelago, Indonesia is prone to earthquakes and volcanic activity due to its location on the so-called Pacific Ring of Fire.