Russia warned of "a new world war" starting in Syria on Thursday after a dramatic day in which Gulf states threatened to send in ground forces.

Foreign and defence ministers of the leading international states backing different factions in the war-torn country met in separate meetings in Munich and Brussels following the collapse of the latest round of peace talks.

Both Russia and the United States demanded ceasefires in the long-running civil war so that the fight could be concentrated against Islamic State of Iraq and the Levant (Isil) - but each on their own, conflicting terms.

But the Gulf states, led by Saudi Arabia, staged their own intervention, saying they were committed to sending ground troops to the country. Their favoured rebel groups have been pulverised by Russian air raids and driven back on the ground by Iranian-supplied pro-regime troops.