The UNHCR said that it was concerned at the decree which contains several provisions affecting refugees and migrants, including fines for NGO vessels engaged in saving lives at sea.

“At a time when European states have largely withdrawn from rescue efforts in the Central Mediterranean, NGO vessels are more crucial than ever,” Roland Schilling, UNHCR Regional Representative to Southern Europe ad interim, said.

“Without them, it is inevitable that more lives will be lost.”

The agency said that sea rescue is a long-standing humanitarian imperative, and also an obligation under international law.

They emphasised that no vessel or shipmaster should be at risk of a fine for coming to the aid of boats in distress and where loss of life may be imminent.

Of further concern to UNHCR is that the decree may result in shipmasters being penalised for refusing to disembark rescued people in Libya.

“In light of the extremely volatile security situation, widespread reports of human rights violations and routine use of detention for people rescued or intercepted at sea, no one should be returned to Libya,” the UNHCR said in an online statement.

Italy’s Interior Minister and Deputy Prime Minister, Matteo Salvini, was quoted on Wednesday as saying that the measures in his new security decree were ready to be applied to a ship run by the Sea-Watch NGO, after it rescued 52 people from a rubber dinghy off the Libyan coast.

He described the German NGO vessel as “a pirate ship that allows some to repeatedly break the law”.

Sea-Watch has on several occasions sought to challenge Salvini’s policy of closing Italy's ports to NGO-run search-and-rescue ships.

The government’s new decree would see organisations that bring migrants rescued at sea to Italy without permission fined up to €50,000.