President Recep Tayyip Erdoğan discussed tensions in Idlib with German Chancellor Angela Merkel late Friday in a phone call.

The cease-fire deal agreed upon between Turkey and Russia topped the agenda in the talks, Presidential sources said. The officials also discussed the Syrian refugee influx during the call.

Erdoğan also told Merkel that Greece's decision to not take into account the Geneva Convention and EU Charter of Fundamental Rights is a violation of international law.

Turkey and Russia reached the agreement on Thursday during a meeting between President Erdoğan and his Russian counterpart Vladimir Putin in Moscow.

The meeting came amid growing tension in northern Syria’s Idlib province, where the Russia-backed Bashar Assad regime offensive has targeted civilians and Turkish soldiers, raising the prospect of a direct clash between Russian and Turkish forces.

The Syrian regime and its allies, Russia and Iran, have consistently broken the terms of the 2018 cease-fire and a new one that began on Jan. 12, launching frequent attacks inside Idlib.

Especially since April 2018, the attacks on the last opposition stronghold dramatically intensified and caused new waves of refugee flows that move toward the Turkish border, putting the country, which already hosts 3.7 million Syrian refugees, into a difficult position.

As a result, Turkey, which has the second-largest army in the transatlantic NATO alliance, has funneled troops and equipment into the region in recent weeks to stop the Syrian regime advance and avoid the wave of refugees.

However, the killing of more than 34 Turkish soldiers in regime attacks last month acted as a tipping point in regional tension. In response, Ankara launched Operation Spring Shield against regime targets in Idlib.