Several migrants have jumped into the sea from a Spanish rescue boat that has been blocked for days from docking at an Italian island in a thwarted bid to reach land on their own.

“We have been warning for days, desperation has its limits,” said Open Arms founder Oscar Camps, who released a video showing four migrants, in orange life vests, swimming towards Lampedusa, while several crew members from the humanitarian group’s ship swam to catch up with them and bring them back aboard.

On Sunday evening, Open Arms said it had urgently requested permission to enter Lampedusa’s port so the migrants, aboard for 17 days, could finally get off. It said their psychological and physical conditions are “at risk”.

“If the worst happens, Europe and Salvini will be responsible,” the charity said in a tweet.

Open Arms, which on Sunday had 107 migrants aboard, has been anchored for days off Lampedusa, a fishing and holiday island between Sicily and northern Africa.

The boat had 147 migrants aboard when it reached Italian waters. In the last few days, 40 have been taken by Italian coastguard vessels to Lampedusa, including a few who were ailing and 27 who said they were minors.

Right-wing Italian interior minister Matteo Salvini has refused docking permission as part of his crackdown on charity rescue boats he says essentially facilitate smuggling of migrants from traffickers’ bases in Libya.

Open Arms carried out its first rescue of this group 17 days earlier, plucking migrants to safety from smugglers’ unseaworthy dinghies off Libya.

Seeking to break the stand-off between Open Arms and Mr Salvini, Spain on Sunday offered its southern port of Algeciras to Open Arms for disembarking, while acknowledging that the destination is far and not suitable for disembarking.

The office of Spain’s caretaker prime minister, Pedro Sanchez, said the offer reflected the “emergency situation” on the boat, and Mr Salvini’s “unconceivable response” in refusing docking.

“But right now, Spain is the only country ready to receive (the boat),” Mr Sanchez’s office said.

But the offer appeared to have been made in vain.

Migrants are evacuated by Italian coastguards from the Open Arms
Migrants are evacuated by Italian coastguards from the Open Arms (Francisco Gentico/AP)

The Spanish NGO’s spokeswoman Laura Lanuza described the situation aboard the Open Arms as untenable.

“There is anxiety, bouts of violence, control is becoming increasingly difficult,” she said.

“To embark on a six-day sailing with these people on board who are at the very limit of their possibilities would be crazy. We can’t put their health and lives at risk.”

Mr Salvini earlier on Sunday told the ship to leave Italian waters and go to Spain, and claimed in a tweet that Open Arms was staying anchored off Lampedusa “just to provoke me and Italy”.

Spain and five other countries have offered to take the migrants in, but Mr Salvini has not let the ship dock.

Open Arms says he is using the 107 migrants for “xenophobic and racist propaganda”.

A Norwegian-flagged ship, Ocean Viking, operated by two French humanitarian groups, has been sailing for days with 356 rescued migrants aboard between Malta and Lampedusa and another tiny Italian island, Linosa, awaiting assignment of a safe port. Mr Salvini vowed to block that ship too.

“Whoever hangs tough wins,” he said. “In Italy there’s no place for traffickers.”