Fifteen-year-old Abou, who had travelled from the Ivory Coast in West Africa, reportedly died after being held in quarantine for 12 days with little or no medical attention.

He was rescued on September 18 in the Mediterranean by the Spanish NGO ship Proactiva Open Arms and transferred with almost 300 other migrants to the GNV Allegra off the coast of Sicily for quarantine.

According to Italian daily La Repubblica, Abou was very ill, dehydrated, malnourished and had evident signs of torture on his body but remained on the ship until September 30, when he was ordered to be transferred to a hospital in Palermo following a medical examination.

But the medical attention came too late and two days later, Abou, who had tested negative for coronavirus twice, fell into a coma.

He died on Monday.

Italy introduced quarantine ships in April, during the height of the coronavirus pandemic, when a government decree mandated the use of ferries moored off the coast to hold rescued refugees under quarantine for 14 days before transferring them to reception centres located around the country.

There are at least three quarantine ships active in Italy, each of which hosts hundreds of people.

The vessels have been criticised as harmful to the physical and mental health of migrants rescued at sea, as well as lacking the proper medical equipment to provide assistance to those on board.

Prosecutors in Palermo on Tuesday launched an investigation into Abou’s death.

“We’re awaiting the results of the autopsy that will be carried out on Wednesday,” lawyer Michele Calantropo said.

“What emerges from preliminary investigations is the presence of only one physician aboard the ferry, which was carrying over 600 migrants.”

Abou is the second person to have died while being held on one of Italy’s quarantine ships.

A young Tunisian man quarantined on a ferry off the coast of Agrigento, Sicily, died in May after becoming upset and jumping into the water.

Forum Antirazzista, a collective of activists and associations in Palermo, held a protest in the Sicilian capital on Tuesday demanding answers.

“We want to know what happens aboard those ships, which even carry children, and whose passengers seem invisible,” it said.