Doctors Without Borders said on Thursday that 470 migrants have been rescued from drowning over the past three days in the Mediterranean and are now aboard the charity's Geo Barents ship.
The Geo Barents is making its way from the waters off Libya toward Sicily, where the crew hopes they will be allowed to disembark the passengers.
It often take several days for Italian authorities to allocate a port to migrant rescue vessels.
Doctors Without Borders said rescues took place in Malta's search and rescue zone but that the island's authorities ignored their "obligations to provide assistance to boats in distress."
Sea rescue groups have long criticized Malta for not helping refugee boats.
