An Italian charity ship rescued 49 migrants at sea off Libya Monday, prompting fresh threats from Rome against all private vessels saving people off the coast of north Africa.
Italy's hardline Interior Minister Matteo Salvini has repeatedly declared Italian waters closed to NGO rescue vessels, leaving several of them stranded at sea in the past in a bid to force Europe to take its share of asylum seekers.
"Mare Jonio has just rescued a rubber boat in distress that was sinking with around 50 people on board," the Mediterranea collective of aid groups and associations that runs the ship said.
The vessel was headed for the Italian island of Lampedusa, "the closest safe port", in deteriorating weather conditions, it said.
"We have formally asked Italy, under whose flag we sail and which legally and geographically bears responsibility, to indicate a port for disembarkation," it added.
Volunteers aboard the Mare Jonio pulled the 49 migrants -- including 12 minors -- from their dinghy some 40 nautical miles off the coast of Libya.
A Libyan coast guard vessel had approached the dinghy while the rescue was underway.
It was not immediately clear whether the Mare Jonio had defied an order from the command centre in Rome telling it to leave the rescue to the Libyans.
"Those on board had been at sea for almost two days... and are exhausted and dehydrated," Mediterranea said in a statement.
Rome, with the support of the EU, has been training the Libyan coast guard since 2017 to intercept boats as part of a controversial deal that has seen a sharp drop in migrant arrivals to Italy.
NGO ships have drawn fire from Rome by attempting on occasion to stop migrants being taken back to crisis-hit Libya, which human rights organisations insist cannot be considered safe for repatriations.
The Italian interior ministry released a directive reiterating "the procedures that must be followed" after sea rescues.
"Saving lives remains a priority, but immediately afterwards the orders of the national authorities of the competent territory must be obeyed, according to the international rules of search and assistance at sea.
"Any deviance from those rules can be read as a premeditated action to bring illegal immigrants to Italy and facilitate human trafficking," it warned.
Should the Mare Jonio request permission to dock, and be refused, it would be the first such stand-off between the Italian government and an Italian-flagged ship.
"Good luck & thank you. We hope the disembarkation outside of Libya will be faster than what we witnessed before," tweeted Vincent Cochetel, the UNHCR's special envoy for the central Mediterranean.
Mediterranea insisted those rescued by the Mare Jonio were "saved twice: from the shipwreck, and from the risk of being captured and returned to the torture and horrors from which they were fleeing."