Turkey has accepted 3.5 million refugees from Syria since the beginning of the seven-year war. Erdogan pledged in June to facilitate the return of refugees.

The Turkish president was speaking on Friday at a summit in Tehran to discuss the fate of the rebel-held province of Idlib, where a bloody military operation is looming.

Erdogan said steps would be taken to prevent further migration from Syria.

OCHA estimates that if an offensive on Idlib were to take place, 800,000 people would be displaced.

Earlier on Friday Erdogan called for a ceasefire and an end to air strikes in the Idlib province, something that wasn't immediately accepted by Russian President Vladimir Putin and Iranian President Hassan Rouhani.

Instead, Putin warned that militants in Idlib planned "provocations," possibly including chemical weapons.

The Syrian government has been repeatedly accused of using chemical weapons in the long conflict.

For his part, Rouhani demanded an immediate withdrawal by American forces in the country.

The US has some 2000 troops in Syria. He added that "we have to force the United States to leave," without elaborating.

"The fires of war and bloodshed in Syria are reaching their end," Rouhani said, while adding that terrorism must "be uprooted in Syria, particularly in Idlib."

Early on Friday, a series of air strikes struck villages in southwest Idlib, targeting insurgent posts and killing a fighter, said the head of the Britain-based Syrian Observatory for Human Rights, Rami Abdurrahman.

Abdurrahman said suspected Russian warplanes carried out the attack.

Australian Associated Press