GENEVA - The World Health Organization and other aid groups on Friday called on authorities in Libya to stop burying flood victims in mass graves after a U.N. report showed that more than 1,000 people had so far been buried in that manner since the country was hit by floods.

A torrent washed away whole districts of Derna, a city in eastern Libya, on Sunday night after two dams collapsed. Thousands were killed and thousands more are missing.

"We urge authorities in communities touched by tragedy to not rush forward with mass burials or mass cremations," said Dr Kazunobu Kojima, medical officer for biosafety and biosecurity in WHO's Health Emergencies Programme, in a joint statement sent out by the U.N. health agency with the International Committee of the Red Cross and the International Federation of the Red Cross and Red Crescent Societies.

The statement called for better managed burials in well demarcated and documented individual graves, saying that hasty burials can lead to long-lasting mental distress for family members as well as social and legal problems.

A U.N. report published on Thursday said that over 1,000 bodies in Derna and over 100 bodies in Albayda had been buried in mass graves after the floods on Sept. 11.

(Reporting by Emma Farge Editing by Miranda Murray)