The European Union foreign service is still assessing the implementation of the EU-Turkey deal, the European Commission's foreign policy spokesperson Peter Stano said Friday.

EU foreign policy chief Josep Borrell "informed EU leaders about the ongoing work" Thursday during the virtual summit of European heads of state and government, he said.

Borell is "in regular phone contact" with Foreign Minister Mevlüt Çavuşoğlu, in addition to expert-level discussions, the spokesperson added.

The EU's diplomatic service is supposed to deliver a report on the implementation and the future prospects of the 2016 EU-Turkey deal on migration.

Borrell said Monday that the assessment would include topics of visa liberalization and customs union as well, which was equally mentioned in the 2016 agreement.

He also assured that continuing the cooperation would be in the "mutual interest" of both parties.

The chief of EU diplomacy was tasked to hold talks with Çavuşoğlu to find means to better implement the deal after President Recep Tayyip Erdoğan's visit to Brussels two weeks ago.

Erdoğan started negotiations with the European Council's President Charles Michel and European Commission's President Ursula von der Leyen.

In March 2016, the EU and Turkey reached an agreement to stop irregular migration through the Aegean Sea, and improve the conditions of more than 3 million Syrian refugees in Turkey.

The deal has been successful in stemming refugee flows, but the EU's reluctance to take in refugees from Turkey, and bureaucratic hurdles in transferring promised funds for refugees, have led to sharp criticism from Turkish politicians.

The EU had pledged 6 billion euros ($6.5 billion) of aid for the refugees, but so far transferred less than half of that, according to Ankara.

Turkish politicians also criticized its European partners for not fully implementing the 2016 agreement and backing away from their political commitments, including visa liberalization for Turkish citizens traveling to Europe, opening new chapters in the accession process, and negotiations on upgrading the EU-Turkey Customs Union.

Earlier this month, tens of thousands of refugees tried to cross the Greek border after Turkish authorities announced they would no longer try to block refugees and migrants from reaching Europe.

The decision came after 34 Turkish soldiers lost their lives in a Syrian regime attack in the Idlib de-escalation zone. The renewed attacks risked another wave of migration to Turkey, which already hosts 3.7 million Syrian refugees and says it cannot take in any more.