European governments are "complicit" in grave human rights violations in Libya through their support for authorities there that often work with people smugglers and torture refugees and migrants, Amnesty International said on Tuesday.

Determined to cut African immigration across the Mediterranean, the governments, via the European Union, have provided support to Libya, trained its coast guard and spent millions of euros through U.N. agencies to improve conditions in detention camps where Libya puts the migrants.

The advocacy group said up to 20,000 people were now held in these centers and subject to "torture, forced labor, extortion, and unlawful killings," adding to similar allegations made by other rights organizations over the past months.