A charity on Monday suggested chartering a plane to fly to Spain 107 migrants blocked off the coast of Italy aboard its boat, to end a stalemate with the Italian interior minister, who won't let private rescue boats into his nation's ports.

The migrants, taken to safety in early August from traffickers' foundering dinghies off Libya, have been aboard the Open Arms vessel as long as 18 days while minister Matteo Salvini refuses to relent on his refusal to let the ship dock at the island of Lampedusa.

Open Arms has been anchored some 300 meters (yards) off the vacation and fishing island for days.

"To give dignity to the shipwrecked, they could transfer them to Catania (Sicily), and from there, in a plane, to Madrid," Open Arms official Riccardo Gatti told reporters on the dock at Lampedusa.

Spain and five other European Union countries last week offered to take the migrants, but until they disembark the distribution plan can't be set in motion.

"To rent a Boeing for 200 persons costs 240 euros ($265) a passenger," Gatti was quoted as saying by the Italian news agency ANSA.

Late Sunday, Open Arms said in an official communication to Italian authorities that if it can't be allowed to disembark the 107 at Lampedusa, the migrants could be transferred to another more "adequate" and faster ship that could take them to one of the ports being offered by Spain.

Gatti said it would cost far more than the cost of a flight for an Italian coast guard ship to take on the migrants and sail them to Spain.

Open Arms, a Spanish charity, has nixed Spain's offer of ports, citing the precarious psychological state of the migrants and the small ship's limitations.

It said Madrid's latest offer, of a port in Spain's Balearic Islands, was still unfeasible, although it would be several hundred nautical miles closer that Spain's original offer of Algeciras, a port just beyond Gibraltar in the far western Mediterranean.

Salvini, who's trying to use an Italian government crisis he provoked to gain the premiership, was scathing in his rejection of Open Arms' insistence that the migrants disembark in Italy. Salvini's anti-migrant tactics have given him soaring popularity among his voter base, which blames illegal migrants for crime.

"Why doesn't Open Arms go to Spain?" he tweeted. "In 18 days, they could have gone back and forth three times from Ibiza and Formentera," two Balearic islands.

In Brussels, European Commission spokeswoman Natasha Bertaud said that the EU's executive arm remains ready to "to start to coordinate a process of relocating the people aboard this ship as soon as disembarkation has taken place."

She said: "Unfortunately, the commission has no power to designate a place for disembarkation."

Bertaud called on all parties to help find a solution.