The chief UN weapons inspector says it will be difficult to find and destroy all of Syria's chemical weapons, but he believes it is achievable.
Ake Sellstrom told the BBC much depended on whether Damascus and the opposition were willing to negotiate.
He said his team concluded after a visit to Syria that the nerve agent sarin was used in an attack in a Damascus area on 21 August.
The UN Security Council is now trying to agree a resolution on the issue.
Western nations blame government forces of Syrian President Bashar al-Assad for the deadly attack in the Ghouta area.
Damascus - backed by Russia - says the opposition forces are to blame.
UN disagreements
Mr Sellstrom told the BBC's Newsday programme that dealing with Syria's chemical arsenal was "doable". "But of course, it will be a stressful work," he added.
"Depending on the position of the Syrian government and the position of the opposition, depending on how much they could negotiate, it could be done.
"It will be a difficult job." Mr Sellstrom also said his team's report may have contributed to Syria saying it was prepared to give up its chemical weapons.
The report, however, did not apportion blame for the attack.
On Tuesday, the five permanent UN Security Council members - France, the UK, the US, Russia and China - met in New York to discuss a resolution on making safe Syria's chemical weapons.
Such a document is seen as a key step in a US-Russia brokered plan under which Syria will disclose its arsenal within a week and eliminate it by mid-2014.
However, there have already been key disagreements over the wording.
France, the UK and US want a resolution carrying the threat of military action but Russia opposes this.
The US and Russia hammered out their plan last weekend after Washington had threatened the Syrian government with military action over a chemical weapons attack in the Ghouta area of Damascus on 21 August.
