ROME (AP) — Italian officials deflected responsibility Tuesday after 108 migrants rescued in the Mediterranean were returned to Libya, a move that humanitarian groups said could violate international law.

The U.N. refugee agency and Amnesty International denounced the decision to take the migrants to Libya. But both Italian Interior Minister Matteo Salvini and Transport Minister Danilo Toninelli insisted that the rescue, carried out by the Italian-flagged Asso Ventotto supply ship, was coordinated by the Libyan coast guard without the involvement of its Italian counterpart.

A press release from the ship's operator, Augusta Offshore, confirmed their account, saying the ship got a call from the Libyan coast guard to respond to a rubber dinghy carrying migrants. A Libyan ship escorted them to shore after the rescue, about 1 ½ miles southwest of the Sabratah oil platform, it said.

The U.N. High Commissioner for Refugees in Italy tweeted that Libya is not a secure port, making such a transfer a violation of international law.

"Not only is it a violation of the right of asylum, but it is an inhumane act toward those 108 people," Amnesty Italia said.

Aid groups say migrants who are returned to Libya risk facing beatings, rape, slavery and other mistreatment.

Nicola Fratoianni, an Italian lawmaker aboard a Spanish-run aid rescue ship, wrote on Facebook that it would be "a very serious precedent" if the Asso Ventotto took the migrants to Libya on the orders of the Italian coast guard.

In its statement, Augusta Offshore said the migrants did not protest when they were transferred onto a Libyan coast guard ship in the port of Tripoli, the closest port.

The new hard-line, anti-migrant Italian government has kept rescue ships run by humanitarian groups from bringing rescued migrants to the country's ports since taking power in May. In addition, it's also planning to furnish the Libyan coast guard with 12 more patrol boats in an effort to prevent smugglers' boats from reaching international waters.

Italy insists the step is necessary to stop human trafficking. Opposition lawmaker Laura Boldrini said, however, that the "collaboration with Tripoli doesn't provide a single guarantee on human rights."

In Brussels, European Commission spokeswoman Natasha Bertaud deferred questions about the rescue to Italian authorities, but confirmed the commission's view that Libya does not meet the necessary conditions to be considered a safe port.