The United Nations Security Council will vote April 12 on a resolution launching an independent investigation of the chemical attack on Syrian civilians last week that prompted U.S. missile strikes.
Diplomats said Britain, France, and the United States slightly revised a resolution they presented last week after the gas attack on the town of Khan Sheikhun, taking into account objections from Russia and China.
The vote comes as U.S. Secretary of State Rex Tillerson is urging the Kremlin to reconsider its support for Syrian President Bashar al-Assad, who he blames for the attack that killed 87 people.
UN diplomats said Russia nevertheless is expected to block the measure. China -- which has also sided with Syria in the past -- plans to abstain.
The draft resolution expresses "horror" at the attack and calls for a joint investigation by the UN and Organization for the Prohibition of Chemical Weapons to determine who is responsible.
The resolution requires the Syrian government to provide information about flights from the Shayrat air base that the U.S. contends was used to launch the chemical attacks, and threatens sanctions against Syria if it does not cooperate.
Russia has called those provisions unacceptable, though President Vladimir Putin has called for an independent investigation.