A senior official of the UN's weather agency has indicated that political turmoil in Libya prevented authorities there from preparing a proper system that could have helped them avoid casualties from massive floods earlier this week.

World Meteorological Organization Secretary-General Petteri Taalas spoke Thursday at a news conference on the deadly floods that were triggered by torrential rain in eastern Libya on Monday.

Taalas said Libyan authorities could have issued warnings and evacuated people if they had had a normally operating meteorological service.

The North African country has long been in chaos with its east and west controlled by different political forces.

Libyan media quote a high-ranking official of the eastern administration as saying more than 5,000 people died in the floods. But the mayor of the eastern city of Derna told NHK that the death toll could exceed 20,000.

Downpours broke two dams, unleashing torrents of water that swept away homes and other buildings across a wide swathe of the city. A senior official of the city told Middle Eastern media that the dams had not been maintained for a long time.

An Egyptian who was in Derna at the time of the disaster told NHK by phone that he had heard an explosive sound before seeing a surge of water. He added that people inside buildings had been unable to escape the flood.