THERESA May has been savaged by opposition politicians for failing to give MPs a vote on the missile strikes against Syria.

The Prime Minister is also under growing pressure over the "legality" of the action.

May has faced scathing criticism for launching the attack alongside the US and France, while MPs are away from parliament.

The Prime Minister was also accused of bypassing the United Nations.

May's opponents said the bombing could be illegal, as they demanded a Commons vote on the attack.

READ MORE: Airstrikes hailed a success as Syria threatened with further action

The missile strikes were in response to a suspected chemical attack on the Syrian town of Douma.

May said she was "confident" of the success of the strikes.

She said the Douma attack had caused "harrowing" scenes of innocent civilians foaming at the mouth.

May said all the indications were that it was a chemical weapons attack and the Government was "clear" Bashar Assad's regime was responsible.

In 2013, David Cameron, May's predecessor, tried and failed to get approval for military action against President Assad

READ MORE: UN council rejects Russia resolution condemning Syria airstrikes

However, May was accused of bypassing parliament, while at the same time slavishly following the foreign policy of the White House.

Nicola Sturgeon has said UK foreign policy should be set by Parliament and not Donald Trump.

The First Minister said the suspected use of chemical weapons in Douma was "sickening".

However, she warned that the latest action risked "dangerous escalation".

Sturgeon said her first thoughts were with service personnel taking part in the strikes, which targeted infrastructure at three sites connected with the Syrian regime's chemical weapons programme.

She said: "Syria's use of chemical weapons is sickening - but the question that the PM has not answered is how this action, taken without parliamentary approval, will halt their use or bring long-term peace.

"Air strikes have not resolved situation in Syria so far - nothing I've heard persuades me they will do so now.

"An international strategy for peace must be pursued - not a course that risks dangerous escalation.

"UK foreign policy should be set by Parliament, not US President."

READ MORE: Syrians mount a show of defiance after ‘perfectly executed’ airstrikes

Scottish Labour leader Richard Leonard said the air strikes were "legally, morally and democratically questionable".

Leonard said: "Political avenues should be exhausted before such a serious step is ever taken, yet the Prime Minister has been rushed into legally, morally and democratically questionable air strikes at the behest of Donald Trump.

"Britain should be taking a lead role in negotiating an end to the Syrian conflict and halting the abhorrent use of chemical weapons, rather than putting more innocent civilians at risk, and British military personnel too."

Scottish Greens co-convener Patrick Harvie MSP said May must agree to a vote on the strikes when MPs return from the Easter recess this week.

Harvie said: "There is no credible basis for believing a wave of air strikes will make the people of Syria safer.

"It is disturbing that Theresa May's government is so weak and so unwilling to answer to parliament or to the people that they allowed a delusional US President to announce an action involving UK forces and on a timescale which made parliamentary scrutiny here impossible.

"Even now, it appears that the Prime Minister will try to oppose a vote in the Commons on the UK's role in this bombing campaign.

"That would be entirely unacceptable even for a majority government, but for a Prime Minister who leads a minority administration it shows astonishing contempt."

READ MORE: Syria air strikes - what we know so far

SNP defence spokesman Stewart McDonald said UK forces were engaged in "gesture bombing with no major international consensus.

McDonald said there was no long term plan to halt the use of chemical weapons or deliver peace".

He said: "Most worrying is that she has acted at the behest of presidential tweets and sidelined Parliament.

"What does this new bombing campaign do to help move Syria towards peace? Nothing.

"Instead, it has the potential to dangerously complicate the war, making matters on the ground worse for the people that the strikes are supposed to help. There is no peace strategy.

"This is not a brave or strong decision by the Prime Minister."

UK Labour leader Jeremy Corbyn also attacked the UK government for launching "legally questionable" air strikes in Syria.

May called the Labour leader ahead of the bombing to discuss the strikes and gave him an updated security briefing.

But the talks failed to persuade Corbyn that launching cruise missiles in response to the chemical weapons attack in Douma was the right course of action.

READ MORE: Airstrikes hailed a success as Syria threatened with further action

Despite Russia repeatedly blocking action against Syria through the United Nations,

Corbyn called for Britain to go back to the group of world powers to secure a resolution that has Moscow's backing.

He was written to the Prime Minister to say he believes the strikes were "legally questionable" and said MPs should have been given a vote.

The Labour leader, however, said the UK must go to the UN to secure a new resolution that has the backing of Russia and the United States along with Iran, Saudi Arabia, Israel, Turkey.

He said an agreement secured in 2013 between then US secretary of state John Kerry and Russian foreign minister Sergey Lavrov on the destruction of chemical weapons in Syria showed an agreement could be reached.

"There is precedent that this process can work, and surely it would have been better to do that than start bombing - and goodness knows what the consequences of the bombing could be," he said.

However, Scottish Tory leader Ruth Davidson also backed the bombing.

She said: "I support the targeted air strikes by the UK, US and France against the Syrian regime's chemical weapons facilities.

"As the head of NATO has stated this morning, the use of chemical weapons is unacceptable and those responsible must be held accountable."