West 'must avert danger of war' over Syria crisis, says Russia's UN envoy - as Trump weighs military options

US president says decision over action will come 'fairly soon' as allies line up behind him

President Donald Trump has said a decision over Syria will come 'fairly soon' (AP)

The Russian ambassador to the United Nations has urged the US and its allies not to take military action over the apparent chemical attack in Syria, saying the immediate priority was to “avert the danger of war”.

International tensions have spiked over the attack, with Washington holding Russia partially culpable for what they believe is the use of chemical weapons on the town of Douma by the regime of Syrian President Bashar al-Assad.

Moscow has backed Syria in denying allegations of the attack, and Ambassador Vassily Nebenzia said he “cannot exclude” war between the US and Russia if President Donald Trump uses missile strikes on Syria, as he has threatened.

“The immediate priority is to avert the danger of war,” Mr Nebenzia said after a behind-closed-doors meeting of the UN Security Council. “We hope there will be no point of no return.”

He added that the presence of Russian troops in Syria, with Moscow backing the government of Mr Assad in the country’s civil war, meant that the world was facing a dangerous situation.

Pressure has been mounting for a coordinated international response, with Mr Trump putting himself front-and-centre on Wednesday in tweeting missiles “will be coming”. On Thursday, in an early tweet, the president made it clear he was still assessing what action to take. “Never said when an attack on Syria would take place,” he tweeted. “Could be very soon or not so soon at all!” He added.

Speaking later from the White House he said: “We'll see what happens. Now we have to make some ... Decisions, so they'll be made fairly soon.”

In the wake of a meeting between Mr Trump and his national security team on Thursday afternoon, the White House said no final decision has been made over what to do regarding Syria, and that the president was still assessing intelligence and speaking to international partners.

Mr Nebenzia has called for another emergency meeting of the UN Security Council on Friday to hear from Secretary-General Antonio Guterres on threat to international peace and security from possible military action against Syria by the US and its allies.

Both Theresa May and French president Emmanuel Macron have said that they are working with Mr Trump to craft a response. Mr Macron has declared that France has “proof” that Mr Assad’s government was behind the attack in Douma, which is believed to killed dozens of people.

“We have proof that last week ... chemical weapons were used, at least with chlorine, and that they were used by the regime of Bashar al-Assad,” Mr Macron said. “We will need to take decisions in due course, when we judge it most useful and effective,“ he told broadcaster TF1.

According to reports by NBC News, US officials are in possession of samples of blood and urine from victims of the attack which suggested the presence of both chlorine gas and an unnamed nerve agent. Two unnamed officials told the outlet they were “confident” in the intelligence, though not 100 per cent sure.

A team of inspectors from international watchdog the Organisation for the Prohibition of Chemical Weapons (OPCW) was on its way to Syria on Thursday to begin an investigation into the suspected chemical weapons attack.

German Chancellor Angela Merkel said on Thursday that it was obvious that Mr Assad’s government had not eradicated all its chemical weapon stocks, as mandated by a 2013 agreement brokered by Russia - which averted possible strikes by both the US and France

“We... must now acknowledge that it is obvious that the destruction was not completely carried out,” Ms Merkel said, noting that there is “strong evidence” that Damascus deployed the chemical weapons, but she ruled out being involved in any military action.

Back in Washington, US Defense Secretary James Mattis told Congress that he believes there was a chemical attack in Syria, but he has concerns over the use of military force.

Mr Mattis, addressing a hearing of the House of Representatives Armed Services Committee, declined to discuss US military planning on Syria, but acknowledged his two main concerns over military action: protecting civilians and avoiding triggering a military escalation that gets “out of control.”

“I believe there was a chemical attack and we are looking for the actual evidence,” Mr Mattis said. He added that the use of chemical weapons was “inexcusable” and claiming that with Russia blocking action being taken by the UN Security Council the US “can sit acquiescent or do something about it.”

US House Speaker Paul Ryan said that Mr Trump has the authority to take action against Syria under Congressional legislation and was against changes to legislation that “ties the hands” of the US military.

He added that the US has an “obligation” to lead an international response to the apparent chemical attack and that president Trump was being “deliberate and careful” in weighing up his options.

Agencies contributed to this report