Two charities on Sunday lambasted Italy for pressuring Panama into revoking its flag from migrant rescue ship Aquarius 2, warning the move deals a "major blow" to humanitarian missions off Europe's southern coasts.

Aquarius 2, the one remaining charity rescue vessel still operating in the central Mediterranean, is currently at sea with 58 survivors on board. The decision by the Panama Maritime Authority (PMA) means that once the ship comes into port it will be de-flagged and will not be allowed to operate again unless it can find a new flag. SOS Mediterranée and Doctors without Borders (MSF) said they were "reeling" from Saturday's announcement by the PMA that it must revoke the registration of the ship owing to what the NGO's termed "blatant economic and political pressure from the Italian government."

"This announcement condemns hundreds of men, women and children who are desperate to reach safety to a watery grave, and deals a major blow to the life-saving humanitarian mission of the Aquarius, the only remaining nongovernmental search and rescue vessel in the central Mediterranean," the NGOs stated, as reported by Agence France-Presse (AFP). They urged European governments to "allow the Aquarius to continue its mission, by affirming to the Panamanian authorities that threats made by the Italian government are unfounded, or by immediately issuing a new flag under which the vessel can sail."

Italy's Interior Minister Matteo Salvini said the Italian government had applied no pressure on Panama. A public backlash against the arrival of hundreds of thousands of seaborne newcomers in the past five years helped put Italy's anti-establishment ruling coalition into office. The Italian government yesterday adopted a security decree which will make it easier to expel migrants and strip them of Italian citizenship. The new bill is "a step forward to make Italy safer," Salvini said on Facebook. He added that it would help Italy "be stronger in the fight against the mafia and [people] smugglers." Parliament has 60 days to vote the bill into law.

Salvini has led a popular crackdown against immigration since his League party and the anti-establishment 5 Star Movement took office in June. Salvini has previously accused SOS Mediterranée and other charities of acting like a Mediterranean "taxi service" for the migrants. He said on Sunday that Aquarius 2 had hindered the work of the Libyan coast guard, ignoring instructions. He said that, according to newspapers, Aquarius 2 was about to have its registration revoked by Panama because it was "illegal and does not respect procedures."

"They can change their name and flag another thousand times but Italy's ports will remain shut to these gentlemen," he said.