ROME (AP) — More than 500 rescued migrants are stuck in the Mediterranean on two NGO boats, as Italy and Malta continue to deny them access to their ports.

French charity group Doctors Without Borders (MSF) said late Monday in a tweet that it had completed "a critical rescue" of another 105 people onto the Ocean Viking, raising the total number of migrants on board ship to 356.

Another 150 migrants remain on board the Spanish charity vessel, the Proactiva Open Arms.

Italy's hard-line interior minister, Matteo Salvini, reiterated Tuesday his intent on making sure the two migrant ships don't enter Italian ports.