Turkey’s Foreign Minister Mevlut Cavusoglu spoke with his Russian counterpart over the phone on Monday.  

According to diplomatic sources, Cavusoglu and Sergey Lavrov discussed the recent development in Syria's northwestern city of Idlib after six Turkish military personnel were martyred in a regime strike earlier in the day.

Turkey and Russia agreed in September 2018 to turn Idlib into a de-escalation zone where acts of aggression are expressly prohibited.

The Syrian regime and its allies, however, have consistently broken the terms of the cease-fire, launching frequent attacks inside the zone, killing at least 1,300 civilians since the agreement.

In a fresh move, Turkey announced on Jan. 10 that a new cease-fire in Idlib would start just after midnight on Jan. 12. However, the regime and Iran-backed terrorist groups continued their ground attacks.

Previously, the Turkish president slammed the Syrian military for attacking Turkish troops in Syria’s Idlib province, cautioning that Ankara will not leave such acts unanswered.

Turkish President Recep Tayyip Erdogan has characterised the current developments in Syria’s Idlib province as "unmanageable". He added that around one million refugees from the province are currently heading towards the Turkish border with the Arab Republic.

He further stated that the number of dead among Turkish soldiers due to Syrian shelling in Idlib had risen to eight and slammed Russia for ignoring Damascus' actions.

UN Secretary-General Antonio Guterres on Saturday called for an immediate cessation of hostilities in northwest Syria.

The UN chief is "deeply concerned" about the ongoing military operation in the region, according to a statement issued by his spokesperson.

The secretary-general underlined that attacks against civilians and civilian infrastructure, such as healthcare facilities, are unacceptable.

"Military operations of all parties, including actions against and by designated terrorist groups, must respect the rules and obligations of international humanitarian law, which include the protection of civilians and civilian objects," the statement said.

Guterres reiterated that there is no military solution to the conflict.

Hundreds of thousands of people in Idlib province have been fleeing toward Turkey as government forces attack the last major stronghold held by the opposition, the UN said, citing media reports.

In a briefing on Wednesday, UN humanitarian chief Mark Lowcock told the Security Council that the fighting in Idlib appeared "more intense than anything we have seen in the last year."

Germany urges international efforts to solve Idlib crisis

Germany on Monday warned against a grave humanitarian catastrophe in northwestern Syria amid recent attacks by the regime and its allies.

Addressing a conference in Berlin organized by the German armed forces, Defense Minister Annegret Kramp-Karrenbauer expressed deep concern over recent clashes and regime attacks targeting civilians in the northwestern Syrian province of Idlib.

“How we can prevent a humanitarian catastrophe there, how can we avoid the expulsion of people trapped in this region…these questions have not been satisfactorily answered yet,” she said.

“I believe that this requires an international approach. Therefore it’s good that we, as the E3 countries [Germany, France and the U.K.], will continue our discussions with [Turkish] President [Recep Tayyip] Erdogan,” Kramp-Karrenbauer said.

Erdogan met with leaders of Europe’s three major powers, Germany, France and the U.K. in December, ahead of a NATO summit in London, and “E3 + Turkey” format summits are expected to continue in the coming months.

Kramp-Karrenbauer’s remarks came after a military escalation in northwestern Syria after Assad regime troops attacked on Monday Turkish soldiers deployed in Idlib to monitor a cease-fire.

At least six military personnel were martyred and seven others injured in intense shelling by Bashar al-Assad regime forces in the region.

Kramp-Karrenbauer, also the leader of Chancellor Angela Merkel’s Christian Democrats, had proposed last year an "internationally controlled security zone" in northern Syria, but could not win the support of her coalition partner Social Democrats.

The recent military offensive of the Syrian regime has led to fears of a humanitarian crisis and another refugee influx towards Europe.

Located in northwestern Syria, Idlib province is the stronghold of the opposition and anti-regime armed groups since the outbreak of the civil war in 2011.

It is currently home to some 4 million civilians, including hundreds of thousands displaced in recent years by regime forces across the war-weary country.

Turkey and Russia agreed in September 2018 to turn Idlib into a de-escalation zone where acts of aggression are expressly prohibited.

Almost 1.5 million Syrians have moved near the Turkish border due to intense attacks in recent months.