Syria still holds 8% of chemical weapons

The deadline has passed for Syria to rid itself of its chemical arsenal but a task force says the country still holds eight per cent of its weapons.

Syria still holds nearly eight per cent of its chemical weapons arsenal as the deadline expired. (AAP)

Syria is still holding nearly eight per cent of its chemical weapons arsenal as the deadline expired for it to be handed over, the task force charged with the operation says.

"We are talking of the remaining 7.8 per cent chemical weapons material that is currently still in country in one particular site," Sigrid Kaag, head of the combined Organisation for the Prohibition of Chemical Weapons-UN task team, told a news conference on Sunday.

She added that "6.5 (per cent) roughly needs to be removed, a small percentage is to be destroyed regardless in the country where it could be done (...) it is a matter of accessing the site".

Damascus needs to "acquit itself of its commitments", Kaag said, adding that there has been "very constructive cooperation".

Under a US-Russian deal negotiated last year, Syria signed up to the Chemical Weapons Convention and agreed to hand over its entire chemical weapons arsenal.

The deal was hammered out after the United States threatened military action against Damascus in response to a deadly chemical weapons attack outside the capital that reportedly killed some 1,400 people.

Activists and much of the international community blamed the attack on the regime, although it denied responsibility.

Damascus has pledged to have all of its stockpile removed from the war-ravaged country by Sunday and the weapons are due to be destroyed by June 30.

But it has regularly missed deadlines in the process, blaming the security situation in the country, which has been ravaged by a brutal civil war that has killed more than 150,000 people.

Syria declared around 700 tonnes of the most dangerous chemicals and 500 tonnes of less dangerous precursor chemicals.