The bodies of 10 people were found in an overcrowded boat carrying migrants off the coast of Libya, apparently having suffocated, Doctors Without Borders said Wednesday.
The charity's Geo Barents rescue ship pulled 99 people from the sinking boat on Tuesday before making the gruesome discovery in the lower deck.
"At the bottom of the overcrowded wooden boat, 10 people were found dead," tweeted the charity, known by its French initials MSF.
In a later statement, it said the air was filled with the smell of fuel, saying the victims probably suffocated from the fumes after 13 hours adrift at sea.
It took two hours to bring the bodies on board the Geo Barents, where they will be kept pending a dignified burial.
MSF described them as "10 avoidable deaths", adding: "How can we accept this in 2021?"
Tens of thousands of people seek to enter Europe each year via the central Mediterranean, leaving from Libya and Tunisia and heading most often for Italy.
But the route is deadly -- 1,236 people have died in the central Mediterranean so far this year, compared with 858 in the same period of 2020, according to Flavio Di Giacomo of the UN's Migration Agency, the IOM.
He tweeted that the Geo Barents rescue "probably avoided other victims", saying it showed "the need to increase patrols at sea".
The boat was the third rescued in 24 hours by Geo Barents in waters around Libya and Malta.
The charity vessel currently has 186 people on board, including 61 minors, the youngest only 10 months old.
They are from various countries including Guinea, Nigeria, Ivory Coast, Somalia and Syria, and set off from Libya, the charity said.
"On a day like this, when we bring 10 corpses on board our ship, we are once again witnessing Europe's unwillingness to guarantee a desperately needed system of search and rescue in the central Mediterranean," said Caroline Willemen, MSF mission head on board the Geo Barents, in a statement.
She said the survivors, some of whom had travelled for hours with the bodies of their dead friends and relatives, urgently needed a safe haven to disembark.