Spain on Monday stepped up criticism of Italian Interior Minister Matteo Salvini's refusal to allow 107 migrants on board a charity vessel to disembark at an Italian port, calling it "a disgrace to humanity".
The Open Arms has been anchored since Thursday within swimming distance of Lampedusa island.
Some have been on board the boat operated by Spanish charity Proactiva Open Arms for 18 days, putting them on track to surpass the record of 19 days which 32 migrants spent stranded on another charity rescue ship, the Sea-Watch 3, in January.