The UK military is to join Nato forces intercepting and returning people trying to reach Europe from Turkey, as David Cameron prepares to meet European leaders to discuss the escalating migration crisis. The prime minister announced that the Royal Navy was deploying the amphibious landing ship RFA Mounts Bay as the first UK contribution to the Nato deployment in the Aegean Sea. The vessel, which carries a Wildcat helicopter, will join naval vessels from Germany, Canada, Turkey and Greece as part of Nato’s first intervention in the migration crisis.

The announcement came several hours after another boat carrying people sank with the loss of 25 lives including at least three children. Fifteen people were rescued after the boat capsized near the Turkish resort of Didim. It comes as European leaders come under increasing political pressure at home to stem the flow of refugees and migrants.

Turkey hosts more than 2.5 million Syrian refugees, and has warned that tens of thousands more who have fled a Syrian government advance on Aleppo were seeking to join them. Greece, as the first point of entry for most people seeking asylum in Europe, is under concerted pressure from European governments to do much more to halt the influx of refugees and migrants from Turkey.

More than 400 people have died so far this year trying to cross the sea to Europe and nearly 10 times as many refugees and migrants crossed in the first six weeks of 2016 compared with the same period last year.