Image copyright AFP Image caption The earthquake sent residents of Padang rushing for higher ground

A 7.8 magnitude earthquake has struck off the coast of western Indonesia, the US Geological Survey (USGS) reports.

There have been no immediate reports of damage.

The USGS said the earthquake struck at 19:49 local time (12:49 GMT). It said the epicentre was 805km (500 miles) south-west of the city of Padang, and 24km deep.

Indonesia's National Meteorological Agency lifted its tsunami warnings several hours after the tremors.

Australian tsunami warnings for Cocos Island, Christmas Island and Western Australia were also lifted.

No tsunami warnings were issued in India or Sri Lanka.

'Roads jammed'

Residents near the city of Padang told the BBC that they felt two earthquakes around two minutes apart.

Jusuf Wiwekananda, a pilot in Padang, told the BBC the earthquake was "very powerful".

"The walls of my hotel room shook and made a loud sound. I have heard there are a lot of people trying to reach higher ground because of the tsunami reports, so some of the roads are jammed."

Telephone communication was reported to be down in the Mentawai island chain, closer to the epicentre.

In 2004, an 8.9 magnitude earthquake triggered the world's deadliest ever tsunami, killing more than 200,000 people.

After that disaster, a more effective tsunami monitoring system was put in place. Warnings are now issued more frequently after earthquakes in the area.

Indonesia lies on the Pacific "Ring of Fire" of plate boundaries, which produces high levels of seismic activity, including frequent earthquakes.