A rescue ship with more than 600 migrants on board is drifting in international waters on after Italy's new interior minister reiterated his decision to stop it from docking in an Italian port.Matteo Salvini, head of the far-right League who campaigned vowing to stop the mass influx of migrants from Africa, blocked the ship over the weekend."Saving lives at sea is a duty, but transforming Italy into an enormous refugee camp is not," Salvini said on Facebook on Monday. "Italy is done bowing its head and obeying. This time there's someone saying no."Italy has been locked in a standoff over the issue with Malta, which has also refused permission for the vessel to dock.The United Nations refugee agency has called on governments to allow those on board the Aquarius to disembark, and "deal with wider issues later".Euronews correspondent Anelise Borges is on board the Aquarius and sent this report:"Aquarius, this search and rescue vessel that is operated by SOS Mediterranée and Doctors Without Borders (MSF), had been at sea for less than 24 hours when several distress calls were recorded by Italian authorities.They directed the teams here to one search area where two vessels were found with more than 200 people on board. It took at least five hours for all these people to be retrieved from the sea and onto this boat to safety."What followed was several other transfers of other people who had been rescued in hours prior to that incident. Right now Aquarius is transferring 600 people to Europe. We have yet to learn their final destination.Doctors Without Borders have been providing care and food for the people here on board and they say they have the situation under control.'We are well prepared and we have food and water, enough to keep these people for two to three days. But this is not what we wish because it’s overcrowded, people are sleeping on the deck. It is not comfortable at all. They are weak, tired, exhausted. So we wish they could have a comfortable place, a dignified place to rest,' MSF project coordinator Aloys Vimard told Euronews.It's a tense situation but everyone on board is calm now. There are 629 people on board the Aquarius including dozens of children and several pregnant women."By law, it will be difficult for Italy to refuse the boat a safe haven, as its own Coast Guard coordinated the rescues.Italy has urged Malta, another European Union country which is closer to Libya, to allow the ship to disembark. But Malta's prime minister says he has told his Italian counterpart, Giuseppe Conte, that he will not take the ship."The Maltese government is concerned at the Italian authorities' directions being given to Aquarius on the high seas which go against international rules, and risk creating a dangerous situation for all those involved," Muscat said on Twitter.Malta allows a small number of emergency evacuations from rescue ships, but has always refused large numbers. The island nation says it already takes in more refugees per capita than Italy.Italy has taken in more than 600,000 boat migrants since 2014.