Syria still holds nearly eight percent of its chemical weapons arsenal as the deadline expired Sunday for it to be handed over, the task force charged with the operation said.

Syria still holds nearly eight percent of its chemical weapons arsenal as the deadline expired Sunday for it to be handed over, the task force charged with the operation said.

"We are talking of the remaining 7.8 percent 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.

She added that "6.5 (percent) 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".

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

Disagreements persist over how its chemical production sites should be destroyed.

Damascus wants to seal the sites, which it says have already been rendered unusable, while Western countries want them completely destroyed, fearing that they may be used in future for chemical purposes.