A 6.2-magnitude earthquake has struck off the Indonesian island of Sumatra, with no immediate tsunami warning issued.

The US Geological Survey (USGS) said the quake hit at a depth of nine kilometres, just over 300 kilometres west of the coastal city Banda Aceh.

The earthquake occurred about 7:00am (local time), USGS said.

"The quake was felt strongly for a few seconds by residents on the west coast," said national disaster agency spokesman Sutopo Purwo Nugroho.

"Some people ran out of their homes."

But he added there had been no reports of damage.

Mochammad Riyadi, from the Indonesian meteorology, climatology and geophysics agency, also said there were no reports of casualties or damages.

"The magnitude may be big but the epicentre is at sea and relatively far away from the nearest city, Banda Aceh," he told AFP.

Banda Aceh was devastated by a huge tsunami in 2004, which killed some 170,000 people in the surrounding region, as well as tens of thousands more in countries around the Indian Ocean.

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

AFP