A wall along the Turkey-Syria border is pictured at the Syrian town of Atimah, Idlib province, in this photo taken from Reyhanli, Hatay province, Turkey. Photo: Reuters / Osman Orsal.

Increased attacks in Syria’s rebel-held Idlib province will spark a new wave of migration, Turkish Prime Minister Binali Yildirim said on Friday, calling on Russia and Iran to rein in a Syrian army offensive near Turkey’s southern border.

The Syrian government offensive supported by Iran-backed militias has gathered pace and displaced tens of thousands of people since November, according to the United Nations.

Turkey, which opposes Syrian President Bashar al-Assad but has been working with his allies Iran and Russia to reduce the fighting in Idlib, says the latest army assault could not have taken place without Tehran and Moscow’s support.

Already host to 3 million refugees from the six-year-old conflict, Turkey fears a further influx across its border from Idlib. The northwestern province is the largest region still held by rebels driven out of other strongholds in Syria, and is home to more than 2 million people, many in need of aid.

“Carrying out increased attacks in Idlib will cause new migration waves and victimization there. This is very dangerous and wrong,” Yildirim told reporters after Friday prayers.

Turkey has been deploying forces inside northern Idlib and setting up bases there after agreeing with Iran and Russia to establish a “de-escalation zone” in Idlib and nearby areas.

“It is very wrong for the Assad regime to launch an offensive, without differentiating civilians, in order to gain land … while the initiative by Turkey, Russia and Iran on a lasting peace in Syria has made progress,” Yildirim said.

“We are discussing this issue with Russia and Iran, we are making our warnings regarding the potentially horrible ramifications of Assad’s attacks,” he said, warning that the fighting was hindering efforts to reach a political solution.

Russia aims to convene a Syria peace congress later this month, though it is not yet clear who will attend.

On Thursday, rebels launched a counter attack against government forces and their allies in Idlib province.