UN chemical weapons experts in Syria
UN chemical weapons experts in SyriaReuters

Syria on Monday launched a blistering verbal attack on "Western" countries that have accused it of using chemical weapons in its deadly five-year conflict, dismissing the allegations as "a campaign of lies", AFP reports.

"The multitude of accusations, made in some Western circles without any tangible evidence, as to the responsibility of the Syrian government in cases of use of toxic chemicals are but a part of a coordinated and repeated campaign of lies," Syria's deputy foreign minister Faisal Muqdad charged.

He was speaking at the annual conference of countries belonging to the Chemical Weapons Convention, a treaty that compels all member states to help rid the world of toxic arms.

Both the regime of Syrian President Bashar Al-Assad and the Islamic State (ISIS) group have been accused of unleashing chemical weapons during the conflict.

A panel set up by the UN, known as the Joint Investigative Mechanism (JIM), has already determined during a year-long probe that Syrian government forces carried out three chlorine gas attacks on villages in 2014 and 2015.

It was the first time that an international inquiry had pointed the finger of blame at Assad and his forces, after years of denial from Damascus.

The panel consisting of UN and experts from the Organization for the Prohibition of Chemical Weapons (OPCW) also found that ISIS – which captured a large swathe of Iraq and Syria in 2014 – was behind a mustard gas attack in Syria in August 2015.

But Muqdad on Monday disputed the JIM's findings, saying its reports were made on "the basis of inaccurate and unconvincing findings" which "undermines the credibility of the OPCW".

The world should instead be concerned about stopping terror groups like ISIS from making and using chemical weapons, Muqdad added.

His words were echoed by Syria's main ally Russia, whose deputy trade and industry minister Georgy Kalamanov said the panel's findings remained "unconvincing and sometimes even partial" against Damascus.

Without naming countries, Kalamanov said there were some who "attempt to use the OPCW to overthrow elected governments. That's unacceptable."

Speaking at the start of the five-day conference in The Hague, OPCW chief Ahmet Uzumcu however stressed that "gaps, inconsistencies and discrepancies" remain in Syria's statements about its own chemical weapons program.

Uzumcu recently said his organization had received more than 20 reports of chemical attacks in Syria since August 1.

Jacek Bylica, the EU's special envoy for disarmament and non-proliferation said more than three years after Syria joined the convention "many and deeply troubling uncertainties regarding the dismantling of the Syrian chemical program remain."

"Syria has manifestly failed to declare its full chemical weapons program," he told delegates.

The EU is "deeply concerned that these chemical weapons might fall into the hands of terrorist groups," Bylica said.

Syria caved to international pressure under a Russia-U.S. brokered deal in September 2013 and agreed to hand over its chemical stockpile to the OPCW for destruction. Since then, however, the OPCW has determined that chlorine has been "systematically and repeatedly" used as a weapon.

Chlorine, widely used for such things as water purification and fertilizers, is exempt from the convention and does not have to be declared to the OPCW.