A U.N. official said last week that most casualties could have been avoided.
“If there would have been a normal operating meteorological service, they could have issued the warnings,” World Meteorological Organization head Petteri Taalas told reporters in Geneva.
“The emergency management authorities would have been able to carry out the evacuation.”
The International Committee of the Red Cross added that it has provided 6,000 body bags to local authorities, as well as medical, food and other supplies distributed to hard-hit communities.
More than 3,000 bodies were buried by Thursday morning, eastern Libya’s health minister, Othman Abduljaleel, said as Derna has begun burying victims of the devastating flood in mass graves.
He added that another 2,000 bodies were still being processed as rescue teams continue searching through wrecked buildings in the city centre for more victims.
Untold numbers could be buried under drifts of mud and debris, including overturned cars and chunks of concrete, that rise up to 13ft high.
But rescuers have struggled to bring in heavy equipment as the floods washed out or blocked roads leading to the area.
After pummelling Greece last week, the storm barrelled through Mediterranean city, which has a population of around 125,000, on Sunday night and blasted citizens with a terrifying wall of water.
As the storm swept through, residents said they heard loud explosions when two dams outside the city collapsed.
Deadly floodwaters gushed down Wadi Derna, a valley that cuts through the city, crashing through buildings and washing people out to sea.
Officials in eastern Libya warned the public about the coming storm, and on Saturday, they ordered residents to evacuate coastal areas, fearing a surge from the sea – but there was no warning about the dams collapsing.
Rescue diving teams are reportedly still combing the sea off Derna in the search for victims.
International aid started to arrive earlier this week in Benghazi, 150 miles west of Derna.
Several countries have sent aid and rescue teams, including neighbouring Egypt, Algeria and Tunisia.
Italy dispatched a naval vessel on Thursday carrying humanitarian aid and two navy helicopters to be used for search and rescue operations.
The dead in eastern Libya included at least 84 Egyptians, whose remains were transferred to their home country on Wednesday.
Libyan media also said dozens of Sudanese migrants were killed in the disaster.
Libya, in crisis following a decade of civil war, is politically divided between east and west.
Public services have crumbled since a 2011 Nato-backed uprising that prompted years of unrest.
The internationally-recognised government in Tripoli does not control eastern areas, where Derna is located.
