Syria's declared chemical arms '100 percent destroyed' - watchdog

Syria's declared chemical arms arsenal has been completely destroyed, capping more than two years of delicate work, the global watchdog charged with eliminating the world's chemical weapon stockpiles said on Tuesday.

"One hundred percent has been destroyed," Malik Ellahi, the spokesman for the UN-backed Organisation for the Prohibition of Chemical Weapons (OPCW), told AFP.

But The Hague-based organisation still remains deeply concerned by reports of the use of sarin and mustard gas in the country, as well as deadly chlorine gas in Syria's brutal civil war.

Under the terms of a historic deal hammered out in September 2013 by US Secretary of State John Kerry and his Russian counterpart Sergei Lavrov, Syria admitted to possessing over 1,000 tonnes of chemical weapons after years of denials and agreed to hand over the whole stockpile for destruction.

The deal averted threatened US airstrikes against Damascus after a sarin gas attack on rebel-held areas near the capital that was blamed by the West and the opposition on Syrian government forces in August 2013, in which hundreds of civilians were killed. 

Under the agreement, Syria's entire chemical arsenal had been due to be eliminated by 30 June 2014, and all chemical effluent by 31 December 2014.

But the timetable slipped badly amid protractions by the Syrian government and complications posed by the civil war.

The last remaining vestiges of the declared stockpile - some 75 cylinders of highly corrosive hydrogen fluoride - were destroyed by the US firm Veolia at its treatment plant in Texas, the OPCW said.

"This completes destruction of all chemical weapons declared by the Syrian Arab Republic," the Hague-based OPCW said in a statement issued on Monday.

"The need to devise a technical solution for treating a number of cylinders in a deteriorated and hazardous condition had delayed the disposal process," it added.

A total of 1,300 metric tonnes of chemical weapons have been removed from Syria, with the majority neutralised on the US Navy ship MV Cape Ray and turned into less harmful effluent.