A rescue boat saved 59 migrants at sea off Libya on Saturday and Italy immediately said it would not welcome them, setting up a fresh stand-off with Malta and adding to tensions among European governments over immigration.
The migrants on board Open Arms, a boat run by the Spanish Proactiva Open Arms charity, include five women and four children, said Riccardo Gatti, head of the organisation's Italian mission.
Italian Interior Minister Matteo Salvini, leader of the right-wing League Party, said there would be no exception to his policy of refusing to let humanitarian boats dock in Italy and added that Malta was the nearest port of call.
"They can forget about arriving in an Italian port," he tweeted.
Maltese Home Affairs Minister Michael Farrugia, shot back on Twitter that the rescue had taken place closer to the Italian island of Lampedusa than to Malta.
He told Salvini to "stop giving false information and involving Malta without any reason."
Gatti told Italian radio broadcaster Radio Radicale that the migrants on board included Palestinians, Syrians and Guineans and were all in good condition.
He later told Reuters that Open Arms had received no authorisation from any country to dock, and did not know where it would take the migrants.
On Wednesday Malta let the German charity ship Lifeline dock in Valletta with 230 migrants on board, after it was stuck at sea for almost a week following Italy's decision to close its ports to rescue vessels run by non-government organisations.
However, Maltese Prime Minister Joseph Muscat said the gesture was a one-time "ad-hoc" resolution to the crisis and the following day Malta announced it would not allow any more charity boats to dock.
European Union leaders on Friday came to a hard-fought agreement over migration that Salvini and Italian Prime Minister Giuseppe Conte said was positive for Italy.
However, the agreement does not oblige other EU states to share the burden of sea rescues.
More than 650,000 migrants have come ashore in Italy since 2014, mostly after being rescued at sea off the Libyan coast by private and public groups. Italy is sheltering about 170,000, but the number of arrivals has plummeted this year.
Despite the decline in arrivals, there are still daily stories of disasters as migrants make the perilous crossing from Africa to Europe. The Libyan coastguard said around 100 were thought to have drowned off Tripoli on Friday.
That tragedy raised the political temperature in Italy, where the government dismissed opposition accusations that it was responsible due to its crackdown on NGOs, and said the best way to save lives was by preventing departures from Libya.
"The fewer people set sail, the fewer die," Salvini said.