Bolivia, one of 10 non-permanent council members and a strong supporter of Russia, requested the meeting to address "the recent escalation of rhetoric regarding Syria and the threat of the use of unilateral actions," according to the request sent Wednesday and seen by AFP.

Trump earlier warned on Twitter that "missiles will be coming" to Syria in response to an alleged chemical attack and that Russia should "get ready."

The meeting will be held immediately after a briefing on non-proliferation of weapons of mass destruction, which is scheduled for 10:00 am (1400 GMT), diplomats said.

The Security Council failed on Tuesday to agree on setting up an investigation of chemical weapons use in Syria, with draft resolutions from Russia and the United States defeated in three votes.

Russia used its veto to block a US-drafted measure, while two other proposals from Russia failed to garner enough votes for adoption.

The United Nations is facing calls for a response following an alleged chemical attack in the rebel-held town of Douma on Saturday that killed at least 40 people, according to medics and rescuers.

The United States is consulting Britain and France about a possible military response. US Defense Secretary Jim Mattis said that the Pentagon was ready to provide military options.

After the three failed votes at the council on Tuesday, Russian Ambassador Vassily Nebenzia implored the United States to change course.

"I would once again ask you, once again beseech you to refrain from the plans that you are currently developing for Syria," he said.

Russia has warned at the council that Western military action in Syria would be illegal and could lead to a wider conflict.