The captain of the Open Arms rescue ship says it must be evacuated immediately because the migrants are "psychologically broken" and the vessel is like a bomb that is "going to explode."
Marc Reig told Euronews that some refugees were threatening to jump into the sea amid mounting frustration with deteriorating conditions.
"They want to throw themselves into the water, this is unsustainable, they cannot go on any longer like this," he said.
"We can no longer bear this situation, every second that passes the bomb is ticking. Either someone cuts the red wire and deactivates this bomb, now, or the Open Arms is going to explode."
The vessel, carrying 134 migrants, has been stranded in Italian waters for weeks as a battle within Italy's coalition has prevented it from docking.
A handful of those with urgent medical needs were accepted by authorities in Lampedusa on Thursday.
However, a doctor on board the Spanish-owned ship says the condition of the remaining migrants was now a “humanitarian emergency.”
“They need to be landed with utmost urgency,” the charity tweeted on Friday evening.
Earlier, six EU nations — France, Germany, Luxembourg, Portugal, Romania, and Spain — agreed to resettle some of those onboard, but the European Commission said the longer-term situation over the vessel was 'untenable'.
"We are witnessing the deterioration of the physical and mental health of the people on board," the head of the Open Arms charity, Oscar Camps, said.
Italian Interior Minister Matteo Salvini has ordered officials to prevent the boat from disembarking the migrants, who were rescued off Libya 16 days ago, in defiance of orders from PM Mario Conte.
The president of the European Parliament, David Sassoli, urged Italian authorities to let the ship enter the port on Friday.
"Today, my office was in contact with the captain of the Open Arms mission who described conditions on board as scarcely tolerable. The situation has become dramatic,” said Sassoli. “The immigrants have been blocked on the vessel for already 14 days just one kilometre off the port of Lampedusa.”
He added: “They are now giving up and are inflicting acts of self-harm, while they lose sense of reality. The hygiene conditions on board are worse than ever and it is necessary to allow an immediate disembarkation of those on board. I hope that the Italian authorities understand the gravity of the humanitarian emergency on board the vessel and agree to let them enter the port today."