IOM Greece reported that the deaths bring the total this year to 41, on the so-called Eastern Mediterranean route linking Africa and the Middle East to Europe, which is one of the busiest routes for migrants.

The agency said that more than half the passengers on the boat had come from three Sub-Saharan African countries: The Democratic Republic of the Congo, Cameroon and Angola.

The seven-meter rubber dinghy they were travelling in, is believed to have left the Ayval?k region of the Turkish coast after midnight on Tuesday morning. According to Christine Nikolaidou of IOM’s office in the country, with a total of 64 passengers.

The rescue operation was conducted by the Greek Coast Guard, the European Union border and coast guard agency Frontex, and the Greek Air Force, with all those on board accounted for.

Among the dead were four adult women, one adult male and two young girls. According to Greek authorities, the victims were retrieved from the water unconscious and were rushed to a local hospital, where their deaths were confirmed, the IOM statement said.

The Eastern Mediterranean route is this year’s busiest sea crossing lane for irregular migrants trying to reach Europe, with 9,660 arrivals to either Greece or Cyprus through 9 June, a slight increase over the 9,352 arrivals reported through 9 June last year.

According to the UN refugee agency, UNHCR, an estimated 15,459 people have risked their lives reaching Europe by sea so far this year, and 427 feared drowned.