Trump urges UN Security Council to extend Syria gas attacks probe

President Donald Trump urged the UN Security Council to extend a UN-led investigation to determine who is behind chemical weapons attacks in Syria, as Russia was expected to cast a veto in Thursday's vote.

"Need all on the UN Security Council to vote to renew the Joint Investigative Mechanism for Syria to ensure that Assad Regime does not commit mass murder with chemical weapons ever again," Trump tweeted.

Russia and the United States have put forward rival draft resolutions on renewing for a year the mandate of the Joint Investigative Mechanism (JIM), tasked with identifying perpetrators of Syria's toxic gas attacks.

Syrian regime leader Bashal al Assad's ally Russia has indicated it would veto the US-drafted measure extending the panel for one year.

Russia has already used its veto power nine times at the UN Security Council to block action targeting its Syrian ally.

The United States, France and Britain accuse the forces of Syrian regime leader Bashar al Assad of carrying out the April 4 attack on the opposition-held Khan Shaykhun village, killing scores of people including children.

UN war crimes investigators have said they had evidence that the Syrian regime air force was behind the Khan Shaykhun attack, despite repeated denials from Damascus.

More than 87 people died in Khan Shaykhun, drawing global outrage and prompting the United States to fire cruise missiles at a Syrian regime airbase from which the West says the attack was launched.

On the ground

Russia maintains that the sarin attack was most likely caused by a bomb set off directly on the ground, not by a Syrian air strike as alleged by the West.

While the Organisation for the Prohibition of Chemical Weapons (OPCW) has established that sarin was used in the April attack, it does not have the mandate to assign blame for the attack, leaving that determination to the JIM.

The JIM has already concluded that Syrian regime forces were responsible for chlorine attacks on three villages in 2014 and 2015, and that Daesh terror group used mustard gas in 2015.