PALERMO, Italy (Reuters) - Italian prosecutors on Monday ordered the arrest of three people suspected of torturing migrants in a detention center in north-west Libya.

The men, a 22-year-old Guinean and two Egyptians aged 26 and 24, are believed to be part of a group that kidnapped and mistreated dozens of people, the judicial order seen by Reuters said.

Prosecutors collected testimony from several migrants detained in the former military base of Zawyia, who said they recognized their former jailers among residents of a migrant registration center in Sicily.

“I have been beaten several times. I suffered real torture that left scars on my body... I was whipped with electric wires,” one of the migrants told magistrates, according to the judicial document.

The migrants said the prison was surrounded by high walls and had a blue gate at the entrance. People were separated according to their sex or ethnic group and guarded by armed men.

The head of the center was described as a short, balding Libyan man called Ossama, who was feared for his brutality.

“Ossama is the most ruthless... due to the torture practised, (he) was responsible for two murders of two migrants,” another migrant told investigators.

Women were systematically raped and prisoners were allowed to call their families to ask for payment in return for their freedom. Those who did not pay were often killed or sold to human smugglers.

Libyan migrant detention centers are often controlled by armed groups. Aid workers and rights groups have long denounced them for violence and appealed for their closure.

But the centers have continued to operate, receiving new arrivals from boats intercepted by Libya’s EU-backed coastguard.

“This investigation... confirms the inhumane living conditions in Libya’s so-called detention centers, and the need to act, including at international level,” said Luigi Patronaggio, chief prosecutor of the Sicilian city of Agrigento.