Italy is determined to stem the flow of illegal immigrants
The Italian navy has transferred more than 200 migrants picked up in waters off the island of Malta to Tripoli under a new agreement with Libya.
The migrants were rescued after they issued a distress call on Wednesday.
Italian Interior Minister Roberto Maroni said the Libyan government's move could mark a "turning point" in the fight against illegal immigration.
He said it could also help resolve an ongoing dispute between Italy and Malta over responsibility for the migrants.
Last month, there was a diplomatic standoff between the two after the authorities in Valletta refused to accept 140 migrants heading for Italy, who were picked up by a Turkish ship inside Malta's search and rescue area.
Malta had insisted that the vessel take the migrants to the island of Lampedusa, where Italy has a detention centre for asylum seekers and illegal migrants, because it was the nearest port of call.
Rome eventually took in the migrants on humanitarian grounds.
Nearly 37,000 migrants landed on the shores of Italy last year, an increase of around 75% over the year before.
The 227 illegal migrants were rescued by an Italian tanker on Wednesday after being spotted on three separate boats.
Italian customs official Francesco Maugeri said they were sent back to Tripoli on Thursday aboard two coast guard boats and a border police boat.
"Some of the migrants were suffering symptoms probably caused by exhaustion and cold" but none had serious health problems, he told the Associated Press.
Speaking on Italian television afterwards, Mr Maroni said he had contacted the Libyan government and arranged the immediate return of the migrants.
He said an accord already existed with Libya covering the return of illegal immigrants but that it had never been successfully put into effect.
The interior minster, a member of the anti-immigration Northern League party, praised Libya's acceptance as a possible "turning point", calling it "a historic day".
He said the deal, if implemented in the future, would be a "breakthrough" that could put an end to rows between Italy and Malta over rescue operations.
Mr Maroni said long-promised joint coastal patrols off Libya by Italian and Libyan boats would start on 15 May.
Laurens Jolles, the representative of the UN High Commissioner for Refugees (UNHCR) in Rome, said he was concerned by Thursday's development.
"I very much recognise the problems that countries such as Italy and Malta are facing," he told the BBC.
"However, I do think it's a worrying trend, because the fact is that there is a member state of the European Union which is engaging in an official, declared policy of push-backs."