Council of Europe Commissioner for Human Rights, Dunja Mijatovic condemned the violence against migrants stuck on the Turkish-Greek border in her latest tweet.

“Violence and intimidation reported against people on the move, NGOs and journalists at the Greek-Turkish border and the Aegean islands must stop. Despite the challenges faced, the authorities must protect human rights, curb violence, investigate and prosecute those responsible,” Mijatovic tweeted.

Greece and Turkey have been at odds over immigration policy after thousands of migrants gathered at the border between the two countries earlier this week.

Turkey hosts 4.1 million refugees, many of whom are Syrian, and under a 2016 agreement with the European Union, it agreed to halt the flow of migrants into Europe in exchange for economic incentives and support.

But the uptick of violence in northern Syria has seen around 1 million displaced people amass south of Turkey's border.