RESQSHIP, which operates a migrant rescue ship called Nadir, said on social media platform X it had found the 61 people on board a flooded wooden boat, with the 10 dead trapped in its lower deck.
RESQSHIP said its crew, in consultation with Italian coastguard authorities, pulled the boat towards the island of Lampedusa.
The charity said two of those who survived were unconscious and receiving medical attention, adding that they critically needed emergency evacuation.
RESQSHIP gave no details about where or when the rescue operation took place, but according to the marinetraffic.com tracking service, the Nadir was off the eastern Tunisian port of Sfax on Monday.
The United Nations has registered more than 20,000 deaths and disappearances in the central Mediterranean since 2014, making it the most dangerous migrant crossing in the world.
Earlier this month, 11 bodies were recovered from the sea off the coast of Libya.
AAP
