Fatalities among refugees heading for Europe across the Mediterranean from Africa rose 18 percent in the past six months – compared to the same period in 2015, said the IOM on Thursday.

William Swing, the general-secretary of the intergovernmental organization on migration issues combining 165 nations, predicted that the casualty trend would worsen further into Europe’s summer months.

The International Organization for Migration (IOM) registered a total of 3693 cases of persons killed or missing from the start of 2016 until the end of June.

More than 2,500 individuals or two-thirds of that total drowned in the Mediterranean on their way from northern Africa to Europe, mainly Italy, said the former US diplomat.

Arrivals in Europe over those six months amounted to just over 238,000.

The virtual closure of the so-called “Balkans route” initiated in February by nations such as Macedonia, Hungary and Austria and the EU’s deal with Turkey to stem arrivals in Greece would hardly dissuade refugees, Swing added.

“It’s like water. One builds a dam and the water flows around it,” Swing said. “Refugees are innovative because they are desperate. When you erect a blockade at one spot, they search for another route.”

The Mediterranean route to Europe was one among nine or ten locations worldwide with refugee crises, he said, citing conflicts in Iraq, Yemen and South Sudan.