The head of the mission overseeing the destruction of Syria's chemical weapons has said that Damascus still holds about eight percent of its stockpile.
Sigrid Kaag urged the government of President Bashar al-Assad to ensure it meets a June 30 deadline to destroy all its toxic chemicals.
Speaking in Damascus, Kaag said 7.5-8.0 percent of Syria's declared chemical weapons material remained in country, at "one particular site".
"However, 92.5 percent of chemical weapons material removed or destroyed is signficant progress," she said.
"A small percentage is to be destroyed, regardless, in-country. That can be done. It's a matter of accessing the site," she added.
She acknowledged the security challenges facing the mission, but said Syria was required to meet its commitments nonetheless.
Under a US-Russian deal negotiated last year, Syria signed up to the Chemical Weapons Convention and agreed to hand over its entire chemical arsenal by June 30 of this year.
Syria already missed an April 13 deadline to destroy all the weapons in accessible locations.
In addition to the remaining chemical material, there is a dispute over whether Syria will have to destroy 12 remaining chemical weapons production sites.
Damascus wants to seal the sites, which it says have already been rendered unusable, but Western countries want them completely destroyed, fearing that they may be reopened in the future.
There are also questions over alleged chlorine gas attacks in Syria in recent weeks, which the regime blames on an anti-government group but activists say were carried out by government forces.
Activists and the West blamed the attack on the regime, which denied responsibility.
Seperately, Syria's parliament speaker on Sunday said four new candidates had announced they would compete in the country's June 3 presidential election, which is expected to return Assad to power.
He has not yet announced his candidacy, though he has strongly suggested he will run.
The four candidates announced on Sunday are Sawsan Haddad, Samir Maala, Mohammed Firas Rajjuh and Abdel-Salam Salameh.
Haddad, the only female candidate so far, was born in 1963 and is a mechanical engineer from Latakia province in the northwest, Assad's Alawite heartland.
Maala is an international law professor from Quneitra province in the south.
Rajjuh was born in Damascus in 1966 and Salameh, born in 1971, is from central Homs province.
They join a businessman, Hassan Abdullah al-Nuri, who studied in the US, and independent MP and former communist Maher al-Hajjar as candidates.
The candidates are all largely unknown, with few details immediately available about their backgrounds or political leanings.