Substantial food and medical aid finally began reaching the desperate survivors of the Philippines super typhoon Saturday, but humanitarian groups warned of huge logistical challenges in accessing devastated, remote island communities.

The unprecedented ferocity of the Nov 8 storm and the scale of destruction had completely overwhelmed the initial relief effort, leaving millions in the worst-hit central islands of Leyte and Samar hurt, homeless and hungry, with no power or water.

Eight days later, a working aid pipeline was in place on the ground, funnelling emergency supplies to those left destitute in the ruins of Leyte's Tacloban city, while helicopters flying off the aircraft carrier USS George Washington brought some relief to outlying areas.

UN agencies said more than 170,000 people had received rice rations or food packets, while the Red Cross and Medecins Sans Frontieres (Doctors Without Borders) said they would have mobile surgical units up and running in Tacloban by the end of the weekend.

"The place really needs to be saturated with relief," Red Cross Asia-Pacific spokesman Patrick Fuller said in Tacloban.

"People literally have nothing. Money is useless here," he said.

Since the arrival of the USS George Washington late Thursday, the US military said it had delivered 118 tons of food, water and shelter items to Tacloban and elsewhere, and airlifted nearly 2,900 people to safety.

Although aid was arriving, relief officials described conditions in the covered sports stadium in Tacloban that served as the main evacuation centre as appalling, with an almost total absence of proper sanitation.

Children and the elderly remained particularly vulnerable, often unable to get to the relief distribution points opening in the city.

"I have money ... but I cannot eat my money," Beatrice Bisquera, 91, a retired school supervisor, said in what remained of her home in Tacloban.

"I need medicine but there is no pharmacy that's open. I'm hungry but the food we stored is gone," she said.

In its last update, the National Disaster Risk Reduction and Management Council put the official death toll at 3,633, with 1,179 people missing and nearly 12,500 injured.

The UN has put the number of dead at 4,460 and said Saturday that 2.5 million people still "urgently" required food assistance.

An estimated 13 million people were affected by the storm, including nearly 1.9 million displaced survivors.

The World Health Organization voiced concern over the welfare of remote communities on 20 smaller islands which posed an "exceedingly complicated" aid challenge.

"Because of the geography of the Philippines -- an archipelago of many islands -- and the fact that so many have been hit by the typhoon, it is essentially like mounting at least seven separate, simultaneous relief efforts," said Julie Hall, the WHO's representative in the Philippines.

"This multiplies the logistical challenges associated with the response," Hall said.

Frustrated with the slow pace of the initial relief effort, a large number of people with relatives in the impacted areas decided to take matters into their own hands.

Filling boxes and sacks with everything from packets of rice to cup noodles and candles, they boarded ferries from Cebu island to Ormoc town on Leyte.

"That's my village," Nick Cantuja said softly, pointing from the ferry as it approached the coast.

"Our house is gone now. Everything... it's gone.

"Yesterday, a Red Cross team was able to reach there but it's not enough," he added.

Providing basic medical care remains a top priority, with initial assessments that half of the 38 medical facilities in the impacted region had been wiped out.

Despite the fears for those living in remote areas, some appeared to have been better prepared for Super Typhoon Haiyan than those in larger towns and cities.

The tiny Camotes islands, between Cebu and off Leyte, took a direct hit that flattened most villages, but out of a population of 89,400 there were only five confirmed fatalities.

Alfredo Arquillano, the former mayor of the islands' largest town, San Francisco, said Camotes residents had been practising typhoon drills for years.

"We knew we were vulnerable, so we made absolutely sure that everybody knew what to do and where to go," Arquillano told AFP by phone.

All 1,000 residents of one of the chain's tiniest islets, Tulang Diyot, were evacuated to a larger island before Haiyan made landfall.

"My goodness, it was a good decision. It's fair to say it saved everyone's life. There is not one house left standing on Tulang Diyot. Everything was wiped out," Arquillano said.