A week after a wall of water rushed through the Libyan city of Derna, sweeping thousands to their deaths, the focus turned Sunday to caring for survivors of the disaster.

Aid is now arriving in the North African country as the world mobilises to help emergency services cope with the aftermath of the deadly flood.

The most recent official death toll, from the health minister of the eastern-based administration, Othman Abdeljalil, is that 3,166 people were killed.

But estimates of the true number of lives lost vary widely, with the World Health Organization saying the bodies of 3,958 people have already been recovered.

Around 9,000 people are still missing after what the WHO's Libya representative Ahmed Zouiten called "a disaster of epic proportions".

Two dams upstream from Derna burst a week ago under the pressure of torrential rains from the hurricane-strength Storm Daniel.

The dams had been built to protect the port city of 100,000 people after it was hit by significant flooding in the mid-20th century.

The banks of a dried riverbed or wadi running through the city centre had been heavily built on, and last week's torrent swept everything before it as it rushed towards the Mediterranean.

A week on, bodies are still being found.

A rescue crew from Malta's Civil Protection Department discovered a beach strewn with dead bodies on Friday, the Times of Malta newspaper reported.

International aid is arriving from the United Nations, Europe and Middle East, offering some relief to the thousands of survivors.

The aid includes essential medicines and emergency surgical supplies, as well as body bags to allow corpses to be moved.

Tents, blankets, carpets, hygiene kits and food have been flown in, along with heavy machinery to help clear the debris.

- Questions being asked -

Questions are being asked as to why the disaster was not prevented, when cracks in the dams have been known about since 1998.

Prosecutor general Al-Seddik Al-Sour has announced an investigation into the circumstances leading to the collapse.

Like much of Libya's crumbling infrastructure, the two dams that had been built to hold back water from Derna fell into disrepair during years of neglect, conflict and division in chaos-ridden Libya.

It is currently ruled by two rival administrations that have battled for power since a NATO-backed uprising toppled and killed longtime dictator Moamer Kadhafi in 2011.

The United Nations has launched an appeal for more than $71 million to assist the hundreds of thousands of people in need.

"We don't know the extent of the problem," UN aid chief Martin Griffiths said on Friday, as he called for coordination between Libya's two rival administrations -- the UN-backed, internationally recognised government in Tripoli, and one based in the disaster-hit east.

The scale of the devastation has prompted shows of solidarity, as volunteers in Tripoli gathered aid for the flood victims.

Survivors in Derna are glad to be alive, even as they mourn the loss of loved ones.

"In this city, every single family has been affected," said Derna resident Mohammad al-Dawali.

Seir Mohammed Seir, a member of the security forces, spoke of a three-month-old girl who lived through the tragedy in Derna.

"Her entire family died, she was the only one who survived."

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