After marathon talks in Russia's southern city of Sochi, Erdogan and his Russian counterpart Vladimir Putin announced the deal just hours ahead of a deadline for Turkey to restart its assault on Syrian Kurdish forces.

The agreement cements Russia and Turkey's roles as the main foreign players in Syria, after US President Donald Trump announced the withdrawal of American forces from the country's north earlier this month.

That announcement cleared the way for Turkey to launch a cross-border offensive on October 9 against the Kurdish YPG militia, viewed by Ankara as "terrorists" linked to the outlawed Kurdistan Workers' Party (PKK).

Turkey has seized control of a "safe zone" inside Syria about 120 kilometres long (75 miles) and 32 kilometres (20 miles) deep.