JAKARTA (REUTERS) - An earthquake of magnitude 6.6 struck off the north-west coast of Indonesia's Sumatra island on Friday, the GFZ German Research Center for Geosciences said.

The quake was at a depth of 10km, GFZ said.

Indonesia's weather and geophysics agency, BMKG, put the quake at 7.2 magnitude and at a depth of 19km but said it had no potential to trigger a tsunami wave.

On Dec 26, 2004, a 9.1 magnitude quake off the coast of north-west Sumatra triggered a tsunami that killed more than 230,000 people in Indonesia, Sri Lanka, India, Thailand and nine other countries.

A Twitter user, Siska Sasmita, said Friday's quake was felt strongly in Padang city on Sumatra's west coast.

"We ran outside the house because the quake was felt for a pretty long time," said Mr Goris Tukan, a resident of Nias island, off Sumatra. He said no damage were seen in his neighbourhood.

Disaster mitigation agency official Filifo Daili said the quake was felt for 20 seconds, and the authorities were still collecting information about its impact.