JEDDAH: Turkish President Recep Tayyip Erdogan issued an ultimatum on Wednesday for Syrian leader Bashar Assad to halt his offensive in the northwestern province of Idlib by the end of this month.

鈥淚f the regime does not pull back, Turkey will be obliged to take matters into its own hands,鈥� Erdogan said. 

He said two of Turkey鈥檚 12 observation posts, set up around a proposed de-escalation zone as part of a 2017 agreement with Russia and Iran, were now behind Syrian regime front lines.

鈥淲e hope that the process of the regime pulling back behind our observation posts is completed in the month of February,鈥� he said. 鈥淚f the regime does not pull back during this time, Turkey will have to do this job itself.鈥�

He said the Turkish military would carry out air and ground operations in Idlib, when necessary.

The Assad regime鈥檚 response was to continue its offensive, which has killed 300 civilians since December and displaced 520,000 people in one of the biggest upheavals of the nine-year war.

Regime forces have seized more than 20 towns and villages from opposition forces and militants in the past 24 hours. 

Russian airstrikes killed three members of the same civilian family near Idlib city on Wednesday, and regime rocket fire killed another civilian in the town of Anjara in the west of Aleppo province.

Earlier in the week, eight Turkish troops and civilians and at least 13 Assad regime troops were killed in the most violent clashes since Erdogan sent fighters to Syria in 2016.

Erdogan said the confrontations between his forces and those of the regime was a 鈥渘ew era鈥� in Syria, and that any further attacks would be 鈥渞esponded to in kind.鈥�

鈥淭he air and ground elements of the Turkish armed forces will freely move in the Idlib region and if needed will launch an operation,鈥� he said.

Erdogan said the latest fighting had sent nearly 1 million civilians moving toward the Turkish border and Syrian territory under Turkish control. 鈥淣o one has the right to place such a weight on our shoulders,鈥� he said. 

The mass displacement has also coincided with a biting winter, and humanitarian aid organizations called on Wednesday for an immediate cease-fire to avoid a humanitarian disaster.

Eight aid groups and charities including Save the Children, Care and the International Rescue Committee called for 鈥渁n immediate cessation of hostilities in addition to immediate access to safety for the millions of civilians currently under fire.鈥�

They said: 鈥淎fter nine long years of suffering for Syrian civilians, a peaceful solution to this conflict is now more urgent than it ever has been.鈥�