THE Syrian Government is bracing itself for a possible US military strike after America, Britain and France agreed that the international community “needed to respond” to the suspected poison gas attack on Douma to uphold the global ban on chemical weapons.

The White House confirmed Donald Trump had cancelled his first trip to Latin America to “oversee the American response to Syria”.

The US President has given a stern warning of retribution, stressing how “nothing is off the table” and that he would make a decision on Washington’s next move by Wednesday.

Vassily Nebenzia, Moscow's ambassador to the UN, has warned of “grave repercussions” should America launch a military strike against Syria.

Theresa May, after chairing a meeting of her so-called “war cabinet”, the National Security Council, spoke to Mr Trump and his French counterpart Emmanuel Macron, all of whom condemned the suspected chemical attack as “utterly reprehensible”.

A Downing Street spokeswoman said the leaders agreed that, if confirmed, it represented “further evidence of the Assad regime’s appalling cruelty against its own people and total disregard for its legal obligations not to use these weapons”.

She added: “They agreed they would continue working closely together and with international partners to ensure that those responsible were held to account.”

On Tuesday night, diplomatic tensions again increased in New York as America and Russia were due to table different motions at the United Nations on how to investigate the suspected Douma attack.

Moscow insists there is no proof any chemical agents were used and has suggested Syrian rebels faked the attack to draw America into the conflict.

The Organisation for the Prohibition of Chemical Weapons said it would send a team to Syria "shortly".

Earlier in East Anglia, Mrs May sidestepped questions about whether or not Britain would become involved in military action.

She said: "This attack that took place in Douma is a barbaric attack. Obviously, we are working urgently with our allies and partners to assess what has happened on the ground.

"If this is the responsibility of Assad's regime in Syria then it's yet another example of the brutality and brazen disregard for their people that they show.”

Technically, the PM does not need the endorsement of MPs to launch swift military action. But, politically, it would be very difficult for her to avoid a parliamentary vote. In 2013 following a chemical attack by the Assad regime her predecessor, David Cameron, lost a vote on Britain staging a military response.

Tony Blair, the former Labour Prime Minister, said the UK should support any US action and warned that if the West did not act, then President Bashir al-Assad would feel he had “carte blanche” to do anything.

William Hague, the former Conservative leader, urged Britain and France to join America in taking “more extensive” military action than air-strikes launched by the US President on Syrian air base last year following a chemical attack on the northern town of Khan Sheikhoun, which killed dozens of people.

His Tory colleague, backbencher and former British Army colonel Bob Stewart, who served as a UN commander in Bosnia, argued the PM should be free to act over military action in Syria without consulting Parliament first, because he did not like the PM being “constrained.”

Jeremy Corbyn, meanwhile, brushed back the suggestion MPs might vote on military action, saying: “At the moment there is no decision to intervene or not.”

The Labour leader went on: “The intervention ought to be to support the United Nations in undertaking an investigation into the chemical weapons attack.”

He added: “There has to be a political solution in Syria. That does mean the US and Russia, instead of engaging in megaphone diplomacy across the floor of the Security Council, saying they will support the reconvening of the Geneva talks and all the countries in the region getting round the table together."

The attack in Douma occurred late on Saturday amid a resumed offensive by Syrian Government forces after the collapse of a truce with the Army of Islam rebel group.

Syrian opposition activists and rescuers said poison gas was used on the rebel-held town near the capital, an allegation strongly denied by the Assad regime.

Families were reportedly found suffocated in their homes and shelters with foam in their mouths. At least 42 people were reported to have died.

Reports have also suggested more than 500 people, mostly women and children, were rushed to medical centres with difficulty breathing, foaming at the mouth, and burning sensations in the eyes.