By Ahmed Elumami and Ayman al-Warfali

DERNA, Libya "I lost my daughter. Her mother is convinced that she is still alive. I am convinced that she is dead," says Ahmed Ashour, 62. "The girl left me with a 3-month-old baby."

A week after the flood that swept the centre of the city of Derna into the sea, families are still coping with the unbearable losses of their dead - and haunted by the unknown fates of the missing.

Ashour's eldest sister is also gone, and her daughter too.

"When we saw what happened to other people, we can accept anything that happened to us," she said.

The centre of Derna is a wasteland, with stray dogs standing listlessly on muddy mounds where buildings once stood. Other buildings still somehow stand precariously above bottom floors that were mostly washed away. The legs of a store mannequin in dusty trousers stick out of the rubble in a ruined shop-front.

Dams above the city burst in a storm a week ago, sending a huge torrent down a seasonal riverbed that runs through the centre of the city of 120,000 people.

Thousands are dead and thousands more missing. Officials using different methodologies have given widely varying figures of the tolls so far; the mayor estimates more than 20,000 people were lost. The World Health Organization has confirmed 3,922 deaths.

"Hopes of finding survivors are fading, but we will continue efforts to search for any possible survivor," Othman Abduljaleel, health minister in the administration that controls eastern Libya, told Reuters by phone.

"Now efforts are focused on rescuing anyone and recovering bodies from under the rubble, especially at sea, with the participation of many divers and specialized rescue teams from countries."

FAILED STATE

The roads into Derna were clogged on Monday with ambulances and trucks carrying in food, water, diapers, mattresses and other supplies.

Western countries and regional states have sent teams of rescue workers and mobile hospitals. Five Greek rescue workers, including three members of the armed forces, were killed in a car crash on Sunday.

The recovery effort has been hampered by chaos in a nation that has been a failed state since a NATO-backed uprising that toppled Muammar Gaddafi in 2011.

Derna is in the east, beyond the control of an internationally recognised government in the west, and until 2019 was held by a succession of Islamist militant groups including branches of al Qaeda and Islamic State.

Residents say the threat to the city from the crumbling dams above it had been widely known, with projects to repair the dams stalled for more than a decade. They also blame authorities for failing to evacuate residents in time.

The biggest threat to survivors may now come from contaminated water supplies.

"The flooding crisis has left thousands of people in the Derna region without access to clean and safe drinking water, posing an imminent threat to their health and well-being," the International Rescue Committee charity said.

"Contaminated water can lead to the spread of waterborne diseases, putting vulnerable populations, especially women and children, at increased risk."

(Additional reporting by Tom Perry and Tarek Amara; Writing by Peter Graff; Editing by Alex Richardson)