Turkish President Recep Tayyip Erdogan has said his government is willing to work with the United States to remove Islamic State militants from their de-facto capital, Raqqa in northern Syria.

But he added only on condition that Syrian-Kurdish forces be excluded from any military operations. Erdogan also indicated that Ankara could also contribute to the retaking of Iraq's second-largest city, Mosul, from ISIL control.

Turkey has sent tanks, warplanes and special operations forces into the region last month. In a mission dubbed "Operation Euphrates Shield", Turkish troops fought both ISIL militants and Syrian-Kurdish militia groups.