ROME (Reuters) - Italian police said on Saturday they had arrested a Ghanaian man for alleged murder, rape, kidnapping and people-smuggling after migrants he is accused of mistreating attacked him at a reception center on the Mediterranean island of Lampedusa.

According to the arrest warrant, the African migrants turned on 20-year-old Sam Eric Ackom, known to his assailants as Fanti, when they recognized him as one of a gang that had kidnapped and tortured them in Libya during their voyage to Italy.

The warrant, issued by police in the Sicilian city of Agrigento and seen by Reuters, illustrates the plight of thousands of migrants fleeing war and poverty who increasingly fall victim to criminal gangs operating in lawless Libya.

Boat migrant arrivals in Italy are up more than 57 percent on the same period last year, according to Italian Interior Ministry figures this month, with about half a million arriving since the start of 2014.

Those who have arrived this year have told of increasing violence and brutality in Libya, where rival factions battle for power and people smugglers operate with impunity amid the chaos left by the 2011 overthrow of longtime ruler Muammar Gaddafi.

The 27-page arrest warrant contains testimony by numerous migrants of the treatment they received after being kidnapped by Ackom and other gang members, including rape, scalding with boiling water and beatings.

The migrants from Ivory Coast, Guinea and Nigeria said they were held in a guarded compound in the Libyan desert where they were threatened with guns and forced to telephone relatives to request money while they were being tortured.

“Every time I had to call home, Fanti tied me up with my feet in the air ... and beat me with a rubber tube in every part of my body, especially the soles of my feet,” said Ivorian Vadro Diomande.

Several migrants said they were tortured with electric shocks and one, Nigerian Efosa Idehen, said Ackom, was “one of the most terrible” of the captors, often electrocuting him by attaching electrodes to his tongue.

Ackom, now in prison, arrived in Lampedusa on March 5 after a rescue ship collected him and a group of migrants when the rubber dinghy they were traveling in ran into trouble in the Strait of Sicily.