Russian President Vladimir Putin has called for a regional "co-ordinating structure" against Islamic State (IS).
Mr Putin reiterated his support for Syrian President Bashar al-Assad, who Western countries and the Syrian opposition have said must go.
The crisis is expected to be high on the agenda as world leaders gather at the UN in New York.
Mr Putin will hold rare talks with US President Barack Obama to discuss the issue later on Monday.
Relations between Russia and the West have been strained over Moscow's annexation of Ukraine's Crimea peninsula last year and support for separatist rebels.
In a separate development, UK Prime Minister David Cameron is expected to soften his stance against Mr Assad in a speech this week.
He is due to tell the annual meeting of the UN General Assembly that Mr Assad could remain temporarily in power at the head of a transitional government.
Mr Cameron - along with Mr Obama and French President
