ANKARA (Reuters) - Eight people died after a boat filled with migrants sank off the western coast of Turkey and another 25 were missing, the Turkish coast guard said on Wednesday.

It was not clear where the boat was headed or where it left from. Hundreds of thousands of migrants crossed the sea channel from Turkey to Greek territory in 2015 before Ankara curbed the flow under a deal it struck with the European Union.

The coast guard said the boat sank off the coast of Turkey’s Izmir province after water began leaking shortly after its departure. There were initially around 35 migrants on the boat in total, the coast guard said in a statement.

Search and rescue operations for the missing migrants were continuing, the coast guard added.

One helicopter, an aircraft and three boats were carrying out the operations off the coast of Izmir’s Karaburun district, it said, adding that gendarme and security forces were also carrying out efforts on the ground.

Turkey became one of the main launch points for more than a million migrants taking the sea route to EU territory in 2015, many fleeing conflict and poverty in the Middle East and Africa.

The influx of migrants was drastically curtailed by a 2016 accord between Ankara and the EU, after hundreds died crossing to Greek islands a few miles off the Turkish shore.

Mediterranean arrivals to the bloc, including refugees making the longer and more perilous crossing from North Africa to Italy, totaled 172,301 in 2017, down from 362,753 in 2016 and 1,015,078 in 2015, according to United Nations data.