Three migrants who were banned from disembarking from a ship in Italy after being rescued from the Mediterranean jumped into the sea in desperation on Monday.
Migrants have become trapped in a stand-off between charity ships and Italy's new hard-right government.
Doctors Without Borders (MSF) said the men were quickly pulled from the water near the Geo Barents ship as it was docked in Catania with more than 200 people on board.
The ship is one of the charity vessels that save migrants who are at risk of drowning during the perilous crossing from North Africa to Europe.
They are now in the crosshairs of new Prime Minister Giorgia Meloni's government.
Shortly after the men jumped — apparently one was trying to save the other two — a dozen other migrants standing on the deck of the ship chanted "Help us", AFP reported.
After days at sea, Geo Barents docked in Catania this weekend and Italian authorities allowed 357 people to disembark, including children, while refusing entry to 215 others.
Near by, German-flagged rescue ship Humanity 1 offloaded 144 people, but still has 35 adult male migrants onboard who were also refused permission to go ashore.
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A government decree issued on Friday said Humanity 1 was only allowed into an Italian port for the time it took to help those in "emergency conditions".
Italy's two-week-old government, led by Ms Meloni's far-right Brothers of Italy party and including Matteo Salvini's anti-immigration League, has vowed to stop the tens of thousands of migrants who arrive on the country's shores each year.
Most come in overcrowded, leaky boats and many die as they try to reach Europe. But Italy has long complained that the EU does not share the burden of managing the problem.
Mr Salvini, who is on trial for blocking migrant boats when he was interior minister in 2019, said on Monday that the arrivals must be stopped.
"They are organised trips, increasingly dangerous, which finance weapons and drugs. They must be cut off," the Deputy Prime Minister tweeted.
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But even as tension rose in Catania, more than 500 people were rescued by Italian authorities and taken to Sicily, the head of the Syracuse administration told AFP.
One of the 215 left onboard Geo Barents was later taken to hospital by ambulance after suffering "acute abdominal pain", MSF said on Monday, bringing the total to 214.
Antonio Nicita, a senator with the centre-left Democratic Party, said he had visited the ship and found "a lot of suffering".
"Many people undressed in front of us to show their scabies infection," Mr Nicita said.
Riccardo Gatti, the chief of search and rescue at MSF, said: "Their situation, their level of psychological stress is very, very high.
"The ship has its limitations in terms of medical assistance. A ship is like an ambulance and people are still in the ambulance."
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The charity SOS Humanity, which operates the Humanity 1, said authorities decided after a "brief" medical examination that the 35 men left onboard its vessel were "healthy" and so did not need to disembark.
But it said no translator attended and there was no psychological evaluation.
SOS Humanity has launched legal action against the Italian authorities for choosing those who have the right to land in Italy.
"If a port is secure, then it's secure for everybody," said the charity's lawyer, Riccardo Campochiaro.
The ship's captain, Joachim Ebeling, has defied the demand to leave the port.
"I'm not going anywhere with these people onboard," Mr Ebeling said on Monday
The UN High Commission for Refugees, the UN Refugee Agency and the International Organisation for Migration urged that the migrants be allowed to leave the ship "without delay".
"Italy's efforts in the disembarkation of some 400 people … are welcomed. However, a solution is urgently needed for all remaining survivors," a joint statement said.
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They referred to two other migrant rescue ships, the Ocean Viking and Rise Above, which have been waiting off Sicily with about 230 and 90 migrants.
Media reports late on Monday said Rise Above had been assigned a port in southern Italy.
A group of civil society organisations, including ActionAid International, Human Rights Watch and the Norwegian Refugee Council, echoed the call for a rapid landing.
Amnesty International has accused Italy of "violating its international obligations", saying "the law of the sea is clear: a rescue ends when all those rescued are disembarked in a place of safety".
