Italy transferred 451 migrants from a big fishing boat onto two border patrol vessels Saturday in the Mediterranean Sea, but the migrants' ultimate destination remained uncertain after Italy's hard-line interior minister insisted they should be sent to Malta or Libya instead.

Interior Minister Matteo Salvini, who has forced migration to the top of Europe's agenda by refusing to let rescue boats dock at Italian ports, vowed to remain firm Saturday as he created yet another standoff with hundreds of migrants stranded at sea.

Italian Premier Giuseppe Conte's office said three ideas were being considered: Redistributing the migrants among European countries, contacting Libyan authorities to arrange for their return, or keeping them on board the ships to screen them for asylum.

Both Italy and Malta refused to let the fishing boat dock. Malta said Friday it had fulfilled its obligations by monitoring the vessel to see if it needed help. Malta says the ship's crew made clear they were heading toward the Italian island of Lampedusa and eventually moved out of Maltese waters.

Salvini and his transport minister insisted Malta should have opened its ports to the ship.

Early Saturday, the migrants were taken off the boat and transferred onto a rescue vessel from the EU border patrol agency Frontex and a ship from the Italian border police.

Salvini's office said he told the Italian premier the two ships should now be directed south toward Malta "or better Libya."

In just one month in office, Salvini has upended years of Italian policy toward migrants by refusing them entry. Italy in general feels that the European Union has left it alone to handle the tens of thousands of migrants coming across the sea every year. Salvini is pressing the EU to step up and take in the migrants who land in Italy and trying to helping Libya to prevent them from leaving.

Aid officials say migrants being returned to Libya are at risk to face abuse, rape, beatings and slavery.