Concerns remained that an unknown number of tsunami survivors in Indonesia's Aceh province have not received any aid, two weeks after the disaster that killed more than 104,000 people there.

Aid groups reported the unprecedented humanitarian operation continued to gather momentum amid enormous logistical and infrastructure problems, but conceded some of the most desperate and isolated communities may not have been reached.

"It's impossible to estimate how many people we're feeding," Maria Theresa De la Cruz, head of relief operations in Indonesia for the International Organisation for Migration (IOM), told AFP. "We don't know whether the food air-dropped is distributed in all areas. In some areas it's organised. In other areas, as soon as the chopper lands, everyone rushes there."

The IOM, which was one of the few foreign non-government organisations operating in Aceh before the December 26 disaster, is coordinating airdrops to areas cut off by road with the US navy.

Another prominent aid group conducting relief missions in Aceh, Oxfam, said there were over 100,000 people in 200 makeshift settlements across the province with populations ranging from 30 to more than 3,000.

Oxfam's regional advocacy coordinator, Mona Latzo, said a lack of coordination among aid groups and the Indonesian government meant there was no way of knowing how regularly some of the settlements were receiving aid.

"It's likely that many people have not received continued aid. With over 200 communities, it's very difficult to keep on top of who is getting what and when," Latzo told AFP.

In Meulaboh, an isolated city on the west coast where more than 28,000 people have died, relief workers said survivors who originally fled to higher ground were being forced by hunger to return to scavenge for food in the ruins.

"Groups of displaced persons continue to flow into Meulaboh from the surroundings," said Bertus Loun of Global Relief. "After no longer being able to find enough water or food [in the mountains], they have begun to walk towards the larger population centers."

The logistical problems at the two main airports serving as hubs for aid distribution throughout Aceh is also continuing to plague relief efforts. The airports – in the provincial capital of Banda Aceh and the city of Medan in the neighbouring province of North Sumatra – remain overwhelmed by the numbers of planes trying to deliver supplies, aid groups said.

Latzo said a flight carrying vital equipment for Oxfam arrived in Medan a week ago, but remained stuck there for five days as they could not get landing permission at Banda Aceh airport because of the massive congestion.

She said Oxfam eventually decided to bring the equipment in by truck, a much longer journey that was extended after one vehicle went missing for two days.

"The [aid distribution] situation has improved but we are still experiencing a good number of challenges and we are trying to be creative and think of many different ways to do our work," Latzo said.

The IOM also said it would begin a steady supply of road convoys from the Indonesian capital of Jakarta to Aceh on Monday to avoid the chaos at Banda Aceh airport. "These road convoys will result in more food becoming available. We are basically getting around the bottleneck at the airport," the IOM's spokesman for Indonesia, Chris Lom, told AFP.

Meanwhile, survivors receiving regular food and water at camps in and around Banda Aceh were experiencing the next painful stage of their recovery: looking for financial security with their homes, businesses and livelihoods destroyed.

"My life is in a mess now. Unless aid funds come to us directly and quickly, we may all have to bury ourselves together with the dead," 20-year-old Anita told AFP as she queued to collect a bowl of rice and potato at a relief centre.

Anita, who worked in a brick factory that was destroyed in the floods, said she would need 25 million rupiah (2,500 dollars) to rebuild her house and for other financial assistance. "But if you ask me what's in store in the future, I just don't know. I don't see any light unless we get some financial aid soon," she said.