United Nations: Secretary-General Antonio Guterres said Syria’s failure to answer questions from the international chemical weapons watchdog about its chemical weapons programme “remains a source of very deep concern.”

While the Syrian regime partially addressed some questions raised by the Organisation for the Prohibition of Chemical Weapons, the UN chief said “other questions regrettably remain unanswered.”

In a letter circulated on Friday transmitting the OPCW’s latest report to the Security Council, Guterres said he continues to urge Syria to resolve all outstanding issues.

OPCW Director-General Ahmet Uzumcu said in the report that he has repeated his requests to Syrian authorities that unanswered questions about its declarations of chemical weapons “remain and require a response.”

Guterres said “the profoundly alarming allegations” of chemical weapons use in the Damascus suburb of Douma on April 7 further underline the need for a new body to determine responsibility for chemical attacks.

The OPCW said on Friday that its fact-finding mission to Douma brought back samples for analysis at OPCW-designated laboratories — a process that could take at least three to four weeks. Its inspectors are only mandated to establish whether a chemical weapon was used, not to apportion blame.

Russia vetoed a Western-backed council resolution in November that would have extended the mandate of a joint UN-OPCW body charged with determining responsibility for chemical attacks, dooming its operation and making accountability exceedingly difficult.

Since then, the US and Russia have been lashing out at each other over the issue of accountability for chemical attacks in Syria, which is a close ally of Moscow. In April, rival US and Russian resolutions to set up a new body to determine responsibility suffered defeats in the council.

Guterres warned that “impunity and the absence of international consensus on accountability are escalating the conflict.”

He reiterated that “any confirmed use of chemical weapons by any party to the conflict is abhorrent, reprehensible and a clear violation of international law” — and perpetrators must be held accountable.

The OPCW report, covering the period from March 24 to April 23, says arrangements for destroying the last two chemical weapons production facilities in Syria “are expected to be finalised in the coming weeks.”

“Once the arrangements are in place,” it said, “destruction operations are expected to take two to three months, subject to security conditions.”