More than 20 people have been killed in fighting over the last week between rival tribes in southern Libya, a medical official said on Sunday, in violence reportedly sparked by an incident involving a monkey.

Witnesses said several homes were hit by rockets and shells in the confrontation.

Nasser al-Jehimi, of the medical centre in Sebha, said since Tuesday, 21 people had been killed and around 100 others injured in clashes between Awled Suleiman tribal members and the Guedadfa tribe of Libya's toppled dictator Muammar Gaddafi.

The casualty toll was for the Awled Suleiman tribe alone as information was not immediately available from another hospital being used for their rivals.