Turkey's President Recep Tayyip Erdogan has accused Syrian government forces of "accelerating its aggression" in the Idlib de-escalation zone by taking advantage of the coronavirus pandemic.

"Turkey will protect its commitment to the March 5 agreement reached with Russia, and will not allow the aggression of the regime," Erdogan said at a cabinet meeting late on Monday.

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Turkey and Russia, which back opposing sides in Syria's war, agreed on March 5 to halt hostilities in northwestern Syria after an escalation of violence there displaced nearly a million people and brought the two sides close to confrontation.

"If the regime, which violates the ceasefire and other conditions of agreement, continues like this, it will pay for it with very heavy losses," he said.

Turkish Communications Director Fahrettin Altun said on Twitter Ankara would not allow the government of President Bashar al-Assad to use the pandemic to escalate military operations.

Our government continues to be focused on the coronavirus challenge at home and abroad but we are also working on foreign policy matters such as those in Syria, Libya & the Aegean Sea. As Pres. Erdogan indicated, the Syrian regime is trying to take advantage of the situation. — Fahrettin Altun (@fahrettinaltun) April 20, 2020

"Our government continues to be focused on the coronavirus challenge at home and abroad but we are also working on foreign policy matters such as those in Syria, Libya and the Aegean Sea," said Altun. "As President Erdogan indicated, the Syrian regime is trying to take advantage of the situation."

Altun also stressed Turkey stands by the March 5 agreement with Russia and is determined not to allow Syrian government "aggression" in Idlib despite provocations.

Clashes in Ras al-Ain

Meanwhile, the Syrian Observatory for Human Rights (SOHR) said clashes among Turkish backed armed groups in Ras al-Ain, a city in Hasakah governorate in northeastern Syria bordering Turkey, had led to the killing of members of al-Mutassim Brigade and the injury of others.

"Sources confirmed that the clashes were caused by a dispute over the sharing of money and royalties they had imposed on residents, as well as the seizure of private property of civilians," the SOHR said in a statement on Tuesday.

The London-based monitoring group said there were casualties among other factions as well, without providing further details.

However, Al Jazeera could not verify the reports independently.