Two French charities that have rescued thousands of migrants from the Mediterranean said Friday they could not continue their sea-based mission because of a disagreement related to the coronavirus.

Doctors Without Borders (MSF) and SOS Mediterranee, which have been rescuing migrants for four years most recently on the Ocean Viking ship, could not agree on how to handle the closure of Europe's ports and borders as a result of the pandemic.

MSF ended the partnership as it wanted to continue regardless of guarantees of safe entry from European governments, whereas SOS Mediterranee said it would be too dangerous.

More than 100,000 migrants tried to cross the Mediterranean last year with more than 1,200 dying in the attempt, according to the UN's International Organization for Migration. 

Many disembark from ports in war-torn Libya and head for Italy, whose government caused outrage among NGOs last week by closing its ports to restrict the spread of coronavirus.

Malta has also closed its ports to migrants, citing the COVID-19 pandemic as a reason. 

"Although both MSF and SOS MEDITERRANEE agree on the vital need for our lifesaving work at sea, SOS MEDITERRANEE felt further assurance from states regarding a place of safety was necessary before sailing," said MSF's Annemarie Loof in a statement.

"For MSF, the humanitarian imperative to act was immediate, with or without such assurance."

MSF said European governments had long been creating a "context of hostility and uncertainty" for NGO rescue missions but must now take responsibility for migrants making the crossing.

SOS Mediterranee's Sophie Beau told AFP she could not guarantee the safety of either the crews or the people being rescued.

"We could not take responsibility for going back to sea when all the indicators are in the red," she said.