Three Sudanese migrants were shot dead on Monday night after their boat was intercepted by the Libyan coastguard and they had been returned to shore.
The International Organisation for Migration (IOM) says that the local authorities opened fire when the migrants attempted to escape from the disembarkation point at Al Khums.
The migrants were among 70 disembarking from a vessel that was intercepted and sent back by the Libyan coast guard, reports Reuters news agency.
Two people were killed on the spot, while a third later died in hospital.
The IOM reiterated its call to the European Union and the international community to end the return of vulnerable people to Libya.
“The use of excessive violence results yet again in the senseless loss of life, amid a lack of action to change a system that often fails to provide any degree of protection,” IOM Libya chief Federico Soda said in a statement.