A powerful typhoon that has killed hundreds of people and wreaked devastation in the Philippines was set to smash into the country again Sunday, forecasters warned.

Typhoon Bopha had looked to be heading away after destroying whole communities in the south, but the official weather agency said Saturday it had unexpectedly turned and would make landfall again, this time in the north.

The agency urged people to prepare for fierce winds of up to 160 kilometres (about 100 miles) an hour and heavy rains when the storm slams into the northern tip of the main island of Luzon in the early hours.

The surprise development piles more pressure on a country that has called for international aid for the south, where floods and landslides sparked by Bopha have flattened whole villages and left tens of thousands of people homeless.

A United Nations aid assessment team flew to the southern island of Mindanao, which bore the brunt of the devastation, on Saturday and witnessed "100 percent destruction", said Imogen Wall, spokeswoman for the UN office for the coordination of humanitarian affairs.

"This is a very poor area where everyone is dependent on agriculture. If people can't earn money from crops they won't be able to put food on the table for their families," she told AFP by telephone.

"They'll need a lot of help in the coming months. This is going to take a long time."

Bopha, the strongest typhoon to hit the disaster-prone Philippines this year, barrelled into Mindanao from the Pacific Ocean with gusts of up to 210 kilometres an hour on Tuesday.

At least 548 people have so far been confirmed dead and about 500 others are missing. Around 212,000 others have been left homeless, according to the civil defence office.

In the isolated hamlet of Marapat on Saturday, about 4,000 survivors had only coconuts to eat, as no substantial aid was yet to reach them, said nursing mother Virginia Dodres.

All the houses had been carried off by floods, and survivors were sleeping 80 to a room on the bare concrete floor of the local school.

They share its two toilets and are doing their washing and bathing at a nearby spring, which is also their only source of water.

Dodres, 38, said church workers with two big pots of porridge arrived Saturday, the first and only relief aid yet to the hamlet, which is near the devastated town of New Bataan. The food was gobbled up within minutes.

Officials said Mindanao's east coast and the banana plantations and illegal gold mines around New Bataan accounted for all but 42 of the known deaths from the typhoon.

Twenty-six corpses were put into donated white wooden coffins and laid on a muddy open space where the New Bataan public market used to stand. A few relatives, and flies attended to them.

Jing Maniqued, an unmarried 37-year-old who previously worked as a maid abroad, did not know where to bury her two sisters since the cemetery had itself been covered by debris. Her parents and a mother are still missing.

"There's nothing left for us here. We will probably leave," she told AFP.

Cedric Daep, a public safety specialist, said desperate survivors looted shops and warehouses in Cateel, one of three hard-hit towns on the Mindanao coast in the early aftermath of Bopha's landfall there.

"The food aid took so long to arrive that the locals broke into whatever building (was) left standing in search of something to eat," said Daep, who was sent to the south to help organise the disaster response.

Pope Benedict XVI issued a call for "brotherly solidarity" and said he was praying for "the victims, their families and the many homeless" in Asia's largest Catholic outpost, where 80 percent are followers of the religion.