ATHENS — A prominent humanitarian group on Thursday blasted Greece over its treatment of asylum-seekers on the island of Lesbos, repeating allegations of illegal deportations back to Turkey and claiming authorities are using hunger as a weapon against some migrants.

Doctors Without Borders, known by its French acronym MSF, said in a statement that the situation for asylum-seekers on the eastern Aegean Sea island is “continuously deteriorating.”

“Many people there have been exposed to violence and have alleged abductions by unidentified masked people, pushbacks that forced them out of Greece, arbitrary detentions, and deprivation of food and shelter,” it said.

The Greek government has ordered an investigation into claims that a group of migrants was illegally deported from Lesbos back to Turkey. Last week’s New York Times report claimed that the migrants were taken onto a Greek coast guard boat that left them in a raft at sea to be picked up by the Turkish coast guard, which returned them to Turkey.

Athens has repeatedly denied persistent allegations that it engages in such deportations, known as pushbacks. Lesbos is a major landing point for thousands of people seeking a better life in Europe, who cross illegally from Turkey in small boats provided by smuggling gangs.

MSF said Thursday that fear of pushbacks was preventing many newly-arrived migrants from accessing its health services, while others who could not be found may have been secretly deported.

“When we are alerted of newly arrived people in urgent need of medical assistance, we spend hours — sometimes days — looking for them as they are often hiding in forests,” Nihal Osman, MSF’s Lesbos coordinator, said. Osman added that since June 2022, MSF had been unable to find 940 people at their reported locations.

The group also claimed that Greek authorities stopped giving food on May 17 to people who had completed the registration process in a Lesbos center for asylum seekers to stay pending examination of their bids.

“The government is using food as leverage to force people to leave the facility,” Osman said. He also described as “dire” conditions at another center where newly arrived asylum seekers are sent for days, saying it’s overcrowded and too remotely located.

There was no immediate comment from the Greek government.

Nearly a million people reached Greece from Turkey in 2015, most landing on Lesbos. Numbers later dropped, and since 2019 Athens has stepped up patrols at sea to further reduce arrivals.