A powerful earthquake, which struck near the city of Padang on Indonesia's Sumatra island today, has killed between 100 and 200 people, a disaster agency official said.

Priyadi Kardono, spokesman for the national disaster agency, said about 500 houses had caved in and around 100 people were buried under the rubble, according to officials in the area.

The 7.6 magnitude quake hit Padang, West Sumatra. Initially thousands of people were believed trapped under collapsed houses and other buildings, but with communications to the area cut, officials have struggled to get details of casualties and damage.

The death toll was likely to rise as many buildings in the city of 900,000 people had collapsed, Vice President Jusuf Kalla told a local TV station in Jakarta.

TV footage showed piles of debris and smashed houses after the earthquake, which caused widespread panic across the city.

Rustam Pakaya, the head of the Health Ministry's disaster center in Jakarta, said that "thousands of people are trapped in the rubble of buildings."

The main hospital had collapsed, roads were cut off by landslides and another local TV station said the roof of Padang airport had caved in. Thousands are expected to spend the night in the open while a full assessment of the damage would need to wait until daybreak.

The disaster is the latest in a spate of natural and man-made calamities to hit Indonesia, a sprawling archipelago of 226 million people.

Kalla said the government was preparing for an emergency response of up to two months.

Welfare Minister Aburizal Bakrie said authorities should prepare for the worst. The damage could be on a par with that caused by a 2006 quake in the central Java city of Yogyakarta that killed 5,000 people and damaged 150,000 homes, he said.

"Hundreds of houses have been damaged along the road. There are some fires, bridges are cut and there is extreme panic here," said a witness in the city, adding that broken water pipes had triggered flooding.

Officials said power had been severed in the city.

The quake was felt around the region, with some high-rise buildings in Singapore, 440 km (275 miles) to the northeast, evacuating staff. Office buildings also shook in the Malaysian capital, Kuala Lumpur.

The Pacific Tsunami Warning Centre cancelled an earlier tsunami alert.

A resident called Adi told a local TV station: "For now I can't see dead bodies, just collapsed houses. Some half destroyed, others completely. People are standing around too scared to go back inside. They fear a tsunami."

"No help has arrived yet," he said. I can see small children standing around carrying blankets. Some people are looking for relatives but all the lights have gone out completely."

Sumatra is home to some of the country's largest oil fields as well as its oldest liquefied natural gas terminal, although there were no immediate reports of damage to those facilities.

Padang, capital of Indonesia's West Sumatra province, sits on one of the world's most active fault lines along the "Ring of Fire" where the Indo-Australia plate grinds against the Eurasia plate to create regular tremors and sometimes quakes.

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