The UN Security Council will vote on whether to extend a UN-led investigation to determine who is behind chemical weapons attacks in Syria, with Russia expected to cast a veto.

Russia and the US were set to go head-to-head in the UN Security Council on Thursday over the investigation mandated by the United Nations into chemical weapons attacks in Syria.

Washington and Moscow have put forward competing draft resolutions on the renewal of the Joint Investigative Mechanism (JIM), with Russia likely to use its veto power for the tenth time on a Syria-related vote to reject the US proposal.

The council is under pressure to renew the task force as its mandate is due to expire at midnight on November 16.

The US extension "preserves the professional objective" of the chemical weapons investigation team, while the Russian proposal would "neuter" it, a UN diplomat told dpa.

Russia has cast doubt on the most recent JIM report, which placed the blame for the April 2017 sarin gas attack in Khan Sheikhoun squarely at the feet of the Syrian government.

Moscow vetoed a previous attempt to renew the investigative mechanism last month, reasoning that the council should wait until the release of the Khan Sheikhoun report.

After the report came out, Russia's Deputy UN Ambassador Vladimir Safronkov called the investigation "deeply disappointing" and "mediocre."

JIM head Edmond Mulet told the council last week that the investigation was unbiased and described how the task force sifted through thousands of documents and considered eight different scenarios as part of its inquiry.

The Hague-based JIM is the joint investigation team of the UN and the Organization for the Prohibition of Chemical Weapons (OPCW).

source: AFP