​​​​​​​HAMILTON, Canada

The UN's deputy to the high representative for disarmament affairs, Adedeji Ebo, emphasized concerns Thursday about Syria's lack of full cooperation with the Organization for the Prohibition of Chemical Weapons (OPCW).

He said Syrian officials' declaration on "chemical warfare agents" is inaccurate and incomplete.

Citing the latest consultations between the OPCW's assessment team and Syrian authorities held in May in Damascus, Ebo told the UN Security Council that the assessment team requested explanations from Syrian officials for the results of samples collected from "two formally declared chemical weapons-related sites."

These results indicated "potentially undeclared activities related to several chemical warfare agents," involving "the full production cycle from research and development to production, testing, and storage."

"Although the Syrian Arab Republic provided some additional information on these results, the OPCW technical secretariat assessed this information as insufficient," he said.

Ebo said that raised the number of unresolved matters from 24 to 26, with seven resolved to date.

"This is an extremely worrying development," Ebo stressed, adding that Syria refused OPCW's proposed dates for the 28th round of consultations.

Saying that the chemical weapons watchdog does not consider Syrian authorities' declaration submitted as "accurate and complete," Ebo urged the Security Council to demonstrate unity.

"I urge the members of this Council to unite on this issue and show leadership in demonstrating that impunity in the use of chemical weapons will not be tolerated," he said.

The Bashar Al-Assad regime signed the Chemical Weapons Convention (CWC) in October 2013, two months after a chemical attack on an opposition-held Damascus suburb killed hundreds of victims.

The UN concluded in 2014 that the attack involved the use of the sarin nerve agent.