"We have told him that this is not a problem for us", Erdogan added. Moving farther south, some 80 kilometers to Raqqa, would be problematic, because Turkish forces would need to pass through Kurdish territory. It said the wounded were evacuated by helicopters.

Separately, Erdogan also called for worldwide support for a 40 mile "safe zone" in Syria along Turkey's border that will incorporate a no-fly zone.

Osman said his rebel group would like such a zone set up in 90 km (55 mile) stretch of the border between the towns of Jarablus and Azaz.

Turkey's President Recep Tayyip Erdogan has suggested he and the U.S. are ready to drive so-called Islamic State (IS) from its Syrian stronghold of Raqqa.

The president had said a specific Turkish role would depend on further talks.

This is the first fatalities of the Turkish operation inside Syria which has been blamed on the IS group.

USA and Russian Federation far apart on Syria peace and ceasefire
In return, the United States would coordinate with Russian Federation against Al-Qaeda, the letter said, without elaborating. A senior USA state department official said earlier that a ceasefire deal could be announced as early as today.

Ankara now wants global support for an operation to take control of a rectangle of territory stretching about 40 km into Syria, creating a buffer between two Kurdish-held cantons to the east and west and against Islamic State to the south.

Turkish President Tayyip Erdogan said in remarks published on Wednesday by the daily Hurriyet that US President Barack Obama had floated an idea of joint action with Turkey to capture Raqqa, the Syrian city that is Islamic State's de facto capital.

Still, Erdogan may be betting that Turkish participation will marginalize the effectiveness of Kurds in the region in the future, analysts say. Power supplies across Syria have been severely disrupted by the war.

On the fifth day of the operation, a Turkish soldier was killed in clashes with Kurdish fighters in northern Syria. Washington sees the YPG as a successful client in fighting Islamic State in Syria, while Turkey calls it a terrorist organization.

But its focus has also been on Kurdish rebels, including the YPG, who are also tackling ISIS and who the West is backing. The Kurdish YPG militia has already captured swathes of territory from Islamic State with support from the US -led coalition against the group. "But if a safe zone happened for the security of our people at the Turkish-Syrian border, this is something excellent that would please us", he said.

Turkey has not put a time limit on its current incursion into Syria, and has not indicated how deep into Syria its troops might go. Canikli told a news conference on Wednesday that the YPG had not yet completely pulled back east.