A rescue vessel operating in the central Mediterranean Sea has had its registration revoked, leaving its future operations in jeopardy.
When the Aquarius next docks, it will have to remove its Panama maritime flag and cannot set sail without a new one.
It is the last private rescue ship operating in the area used for crossings from Libya to Europe.
The charities running the vessel accuse the Italian government of pressuring Panama into deflagging the Aquarius.
The two groups which lease it, Médecins Sans Frontières (MSF) and SOS Mediterranée, say they were notified of the decision by the Panama Maritime Authority (PMA) on Saturday.
The authority is said to have described the ship as a "political problem" for the country's government, and said Italian authorities had urged them to take "immediate action" against them, according to SOS Mediterranée.
Italy's Interior Minister Matteo Salvini, who has previously described the aid boats as a "taxi service" for migrants, denies his country put pressure on Panama.
On Sunday, he tweeted he didn't even know what prefix Panama has for telephone calls.
Mr Salvini has been a prominent figure in a public immigration crackdown in Italy since his government, a coalition between the right-wing League party and the anti-establishment Five Star Movement, came to power in June.
He has frequently come into conflicts with rescue ship operators and last month was involved in a public stand-off about the disembarkation of 150 migrants on a coast guard ship on the island of Sicily.
According to the United Nations, more than 1,700 migrants have died trying to cross to Europe in 2018.
The Aquarius has been operating in the area since February 2016, finding itself at the centre of diplomatic stand-offs in recent months over disembarkation.
It was under the flag of the Gibraltar Maritime Administration until August this year, when it was given "notice of removal" and re-registered with Panama.
The ship's operators say they were notified of the new decision while on a current mission, and say they have 58 survivors on board from two boats they found in distress.
Once it docks, the vessel will now be de-flagged and will not be able to set sail again without being registered with a new maritime authority.
In a joint statement, the charities insisted they were in "full compliance" with maritime law and denounced the decision as condemning hundreds to death.
The statement asks for European governments to step in to allow the vessel to continue its operations by either reassuring the Panamanian authorities or issuing it a new flag.