GUNUNGSITOLI, Indonesia - Strong aftershocks rattled Indonesia's earthquake-devastated Nias island on Thursday as international aid flowed in and rescuers pulled survivors and bodies out of the rubble of collapsed buildings. At least three tremors rocked the area off the west coast of Sumatra island, one of them measured at 6.3 on the Richter scale by the Hong Kong observatory, causing alarm as rescue efforts and body recovery operations entered a third day.

French firefighters pulled a woman from the rubble of her home alive in the early morning, more than 48 hours after the massive 8.7 magnitude quake struck on Monday night, footage shot by Australia's Seven Network television showed.

"Hot, hot," the long-haired woman identified as Suri said after being pulled out. "My daughter and my sister are dead. They were in the living room."

As many as 2,000 people are feared to have died and many more are believed trapped under the rubble, according to Indonesian officials. A U.N. statement said some 500 were confirmed killed.

Hungry survivors who fled to the hills for fear of massive waves similar to the Indian Ocean tsunami that struck the area three months ago were returning to the main town, Gunungsitoli.

"For the last two days we have been staying up in the mountains because we are afraid of a tsunami. But we have heard there is no chance of a tsunami now, said Ama Rori, 50, a civil servant with his wife and family.

"We have got nothing. They say they will hand out food today. We just have to wait."

Terrible Injuries

Indonesian President Susilo Bambang Yudhoyono was due to arrive on the island for an overnight stay later in the morning, a palace spokesman said.

Nias regent Binahati Baeha told Reuters in Gunungsitoli that aid was now flowing better.

"Aid has come, there has been some progress," he said, adding that hundreds of Indonesian soldiers on the island were engaged in rescue and body recovery work.

But Ole Hauge, delegation head for International Federation of Red Cross and Red Crescent Societies in Jakarta, said some parts of Nias and outlying islands were still hard to reach.

"We have available enough relief items in the country after the tsunami ... now it's more a question about how to bring it in. It's looking better today because we are able to bring in fuel and transport it directly to the city."

A contingent of Australian medics had also arrived on the island. Three Singaporean Chinook helicopters ferried the worst injured off the island to the Sumatran mainland.

Australian Foreign Minister Alexander Downer on Thursday revised down the number of Australians missing following the earthquake to four, from 15. He said an Australian medical team had reported treating terrible injuries.

"The reports that I have had in now overnight are, I must admit, pretty bad," he told Australian radio. "It has been a very significant humanitarian crisis."

British Missing

The British embassy in Jakarta said some of its nationals were missing.

"We can confirm that a small number of British nationals have been reported missing in the region ... We're not aware of any British casualties but we're still checking," said Faye Belnis.

Crucial aid began flowing into Nias on Wednesday as international agencies and the United Nations diverted efforts from Aceh province on Sumatra, which was hardest hit by the tsunami that left more than 220,000 Indonesians dead or missing.

The U.S. Navy hospital ship Mercy and supply ship Niagara Falls, which carries three helicopters, were expected to arrive off Nias in about six days. Japanese medics are also due soon.

Large parts of Nias, famed as a surfing paradise, have been damaged and much of Gunungsitoli has been flattened.

Several hundred people are reported to have died on the isolated Banyak island group just north of Nias.

"The damage is huge, but at this stage we cannot calculate the cost," Public Works Minister Djoko Kirmanto, who is visiting Nias, told Reuters.

"The lack of equipment has been slowing down the work. Heavy equipment is on the way. Four excavators will arrive today."

A Reuters reporter on a ferry arriving at Gunungsitoli laden with troops, foreign volunteers, heavy lifting equipment, ambulances and other vehicles said the port was congested with ships, mostly from the Indonesian navy, bringing aid.

The imperative, one doctor on the ferry said, was to tend to the injured as soon as possible.

"People with broken bones need to have them set or there will be a lot of complications and infection," said Bill Sears, 65, a paediatrician and professor from California.

"We want to get there before that happens," he said.

Additional reporting by Dan Eaton, Jerry Norton and Stuart Grudgings in Jakarta