At least 1,100 people have been killed in the powerful earthquake that hit the Indonesian island of Sumatra, said the UN humanitarian chief on Thursday.

John Holmes said the latest figures "suggest the death toll has risen already to 1,100" and in all probability would likely rise given that thousands of people are still trapped under rubble and even more left homeless.

The 7.6-magnitude earthquake that hit close to Padang on Wednesday has been followed up by a series of jolting aftershocks. Telecommunication, electricity and water supplies have been cut off. Roads have become inaccessible due to landslides.

Emergency relief workers distributed relief goods on Friday, October 02, 2009 [Xinhua Photos]

A UN inter-agency team has arrived in Padang, while a UN Disaster Assessment and Coordination mission is expected to arrive on Friday.

There are "many hundreds of injured people as well," said Holmes, "and again these numbers, I fear, will rise as more information becomes available."

The UN will decide whether to launch an emergency appeal or take money from the organization's Central Emergency Relief Fund, he added.

Wednesday's earthquake struck 55 miles under the sea, according to the U.S. Geological Survey.

Then on Thursday morning, a 6.8-magnitude aftershock struck close to Padang, with no immediate reports of deaths or injuries, according to local media reports.