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The Italian government stepped up its efforts to discourage migration Sunday by telling a Spanish aid group it didn't need help rescuing 1,000 migrants from six dinghies because it had passed responsibility for the Mediterranean Sea mission to Libya's coast guard.

The hard-line interior minister in Italy's new populist government, Matteo Salvini, said it was appropriate for the Libyans to take charge of the rescue "without the NGO vessels interrupting and disturbing them."

Since taking office at the beginning of the month, Salvini has launched a crackdown on private European-flagged rescue ships. He ignited a continentwide debate by refusing them ports to disembark their migrant passengers, accusing aid groups of effectively working as taxis for Libya-based people smugglers.

Italian Premier Giuseppe Conte brought a proposal for revamping how the European Union manages migration to an emergency leaders' meeting Sunday in Brussels. Salvini plans to go to Libya on Monday.

Amid the flurry of diplomacy, the rescue ship of German aid group Mission Lifeline remained stranded Sunday off Malta with 234 migrants aboard and no port at which to dock after both Italy and Malta refused to give authorization. And Danish-flagged commercial liner Alexander Maersk remained off Sicily's coast waiting for a port to disembark the more than 100 people it had rescued.

"Dear Matteo Salvini, we have no meat on board, but humans," said a tweet on Mission Lifeline's account. "We cordially invite you to convince yourself that it is people we have saved from drowning."

A new emergency was unfolding Sunday. Spain's Proactiva Open Arms, an aid group whose ship has rescued thousands of migrants in the Mediterranean, raised the alarm that Italy's coast guard had received distress calls from a half-dozen migrant boats carrying a total of around 1,000 people.

In a tweet, Proactiva said the Italian coast guard sent out a general advisory to all ships in the area but told the group's crew: "We don't need your help."

The Italian coast guard acknowledged it had received the distress call and sent out an advisory, but said it handed off the rescue operation to Libyan coast guard authorities, who assumed responsibility.

Salvini said the private aid groups, whom he accuses of being financed by Hungarian-American billionaire George Soros, "should know that Italian ports are and will be closed."

Before Italy's new coalition government was installed, Italy already worked to bolster the Libyan coast guard's ability to patrol its coasts and to bring back migrants who launched from its shores.

Human rights organizations have criticized the practice, alleging that migrants are abused in Libya and the North African country hardly constitutes a "safe" port of call, as called for by international law.