The charity rescue ship, Emergency, rescued 50 migrants from a wooden boat in international waters off Libya on Monday, while seven others were found dead, the charity said.
Two people are in critical condition and suffering from suffocation and needed urgent medical evacuation, Emergency said in a statement sent to Reuters, without giving further details.
The survivors said they had left the Libyan coastal town of Zuwara on August 16 and were from Somalia and Egypt, the charity said.
The group of migrants included 45 males, five females and 29 of them were unaccompanied minors, it added.
The International Organization for Migration (IOM) said last week that known migrant deaths in the central Mediterranean have risen sharply, even as the number of migrants crossing the route has declined amid tougher European policies.
