The European Union's chief executive, Ursula von der Leyen, expressed sympathy with Turkey over the conflict in Syria on Monday but said it was impermissible for Ankara to let refugees and migrants on its territory cross into Europe, Reuters reports.
Greek police clashed over the weekend with thousands of migrants seeking to enter the EU from Turkey, which has kept a lid on migration from the Middle East into Europe since 2016 in exchange for funds to help refugees.
"I acknowledge that Turkey is in a difficult situation with regards to the refugees and the migrants. But what we see now cannot be an answer or solution," she told a news conference.
Von der Leyen will visit the Greek-Turkish border on Tuesday and Boyko Borissov, the prime minister of Bulgaria – which also shares a border with Turkey – is due to meet Turkish President Tayyip Erdogan in Ankara later on Monday.
READ: Greece pushes back migrants after Turkish border 'onslaught'
The 27 EU states are struggling to agree a joint position vis-à-vis Turkey, which says it will no longer honour its 2016 deal with the EU as another escalation of the war in Syria sends a new wave of refugees to its own soil.
The EU's ties with Ankara have long been strained over human rights concerns, Erdogan's sweeping crackdown on critics following a botched 2016 coup against him and, more recently, hydrocarbon drilling off Cyprus.
The EU has also been bitterly divided on how to share out the burden of caring for refugees and migrants reaching its territory since a 2015-26 spike in arrivals all but overwhelmed Europe.
The chaotic arrival of more than a million people back then strained the EU's security and welfare services, and also fuelled support for right-wing, eurosceptic and anti-immigration parties in many member states.