Major powers close to UN-brokered peace talks on Syria are discussing the possibility of a federal division of the country that would maintain its unity as a single state while granting broad autonomy to regional authorities.

Major powers close to UN-brokered peace talks on Syria are discussing the possibility of a federal division of the country that would maintain its unity as a single state while granting broad autonomy to regional authorities, media reports said.

Speaking to Reuters on condition of anonymity, a UN Security Council diplomat said some major Western powers, not only Russia, have also been considering the possibility of a federal structure for Syria and have passed on ideas to de Mistura.

"While insisting on retaining the territorial integrity of Syria, so continuing to keep it as a single country, of course there are all sorts of different models of a federal structure that would, in some models, have a very, very loose centre and a lot of autonomy for different regions," the diplomat said.

He offered no details about the models of a federal division of authority that could be applied to Syria. Another council diplomat confirmed the remarks.

The biggest sticking point in the peace talks remains the fate of Assad, who Western and Persian Gulf Arab governments insist must go at the end of a transition period envisioned under a roadmap hammered out in Vienna last year by major powers. However, Russia and Iran say the Syrian people themselves must decide.

In a September interview, President Assad did not rule out the idea of federalism when asked about it, but said any change must be a result of dialogue among Syrians and a referendum to introduce the necessary changes to the constitution.

"From our side, when the Syrian people are ready to move in a certain direction, we will naturally agree to this," he said at the time.

The co-leader of Syrian Kurdish PYD party, which exercises wide influence over Kurdish areas of Syria, has made clear the PYD was open to the idea.

"What you call it isn't important," PYD's Saleh Muslim told Reuters on Tuesday. "We have said over and over again that we want a decentralized Syria - call it administrations, call it federalism - everything is possible."

This week, Syria's Saudi Arabian-backed opposition rejected a suggestion by Russia, which like Iran supports Assad's government and has intervened militarily on its side, that the peace talks could agree a federal structure for the country.

"Any mention of this federalism or something which might present a direction for dividing Syria is not acceptable at all," Syrian opposition coordinator Riad Hijab said.