US Secretary of State John Kerry said Tuesday that Syria could be weeks away from a "big transition", following on from international talks in Vienna at the weekend.

US Secretary of State John Kerry said Tuesday that Syria could be weeks away from a "big transition", following on from international talks in Vienna at the weekend.

"We are weeks away conceivably from the possibility of a big transition for Syria," Kerry said after talks with French President Francois Hollande in Paris.

Kerry said there was now a "genuine process with possibilities" to unlock the war in Syria, which has cost 250,000 lives over nearly five years.

"We have found a common agreement on principles (and) established a concept of giving life to a negotiation with Iran and Russia at the table, which is unique in the last four and a half years," Kerry said.