Russian and Turkish delegations discussed the tense situation in the northwestern Syrian province of Idlib in Moscow on Monday.

The talks will also continue on Tuesday, the Turkish Foreign Ministry said in a statement following the talks, stressing the necessity to rapidly reduce tensions and prevent further worsening of the humanitarian situation. 

Turkish Deputy Foreign Minister Sedat Onal is leading Turkey's delegation at the closed-door meeting in the Russian Foreign Ministry in Moscow, while Russia's Presidential Envoy for Syria Sergey Vershinin is heading the counterpart group.

Both delegations include diplomats, as well as representatives of military and intelligence services.

Earlier on Monday, Russian Foreign Minister Sergey Lavrov told reporters that Moscow hopes the meeting would contribute to de-escalating the tensions.

"All the facts are on the table. Military representatives of both the Russian Federation and Turkey, who are on the ground in Syria, in the province of Idlib, examine the changes in the situation in constant contact with each other," he said in Munich.

The two sides' militaries had a full mutual understanding, he also said, adding: "I hope they have ideas that will allow us to de-escalate this situation, basing on the agreements reached by the presidents of Russia and Turkey."

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

But more than 1,800 civilians have been killed in attacks by regime and Russian forces since then, flouting both the 2018 cease-fire and a new one that started on Jan. 12.

UN urges ceasefire to avoid catastrophe in NW Syria

The UN's humanitarian affairs chief called Monday for an immediate ceasefire to be implemented in northwest Syria to prevent "the biggest humanitarian horror story of the 21st Century."

Mark Lowcock said the "indiscriminate" violence in the region has reached "a horrifying new level," and has displaced some 900,000 people since a Syrian regime offensive backed by Russia and Iran began in early December.

The displaced "are traumatized and forced to sleep outside in freezing temperatures because camps are full," Lowcock said. "Mothers burn plastic to keep children warm. Babies and small children are dying because of the cold."

The violence has resulted in medical facilities, schools, homes, mosques and markets being hit, Lowcock said, without naming the perpetrators. He warned that the conditions are such that there is now a "serious risk" of disease outbreaks, and essential infrastructure is already failing.

"A huge relief operation, across the border from Turkey is underway, but it is overwhelmed. The equipment and facilities being used by aid workers are being damaged. Humanitarian workers themselves are being displaced and killed," Lowcock warned.

"The biggest humanitarian horror story of the 21st Century will only be avoided if Security Council members, and those with influence, overcome individual interests and put a collective stake in humanity first. The only option is a ceasefire."

In September 2018, Turkey and Russia agreed to turn northwest Syria's Idlib province into a de-escalation zone in which acts of aggression are expressly prohibited.

But since then more than 1,800 civilians have been killed in attacks by regime and Russian forces, flouting both the 2018 cease-fire and a new one that started on Jan. 12.

The Syrian regime's advances have sent hundreds of thousands of Syrian civilians fleeing towards the border with Turkey, which already hosts more than 3.7 million refugees.