Only a quarter of Britons backed the UK’s decision to launch air strikes in Syria to punish the country’s regime for allegedly using chemical weapons, a new poll has revealed.

The exclusive survey for The Independent shows more people opposed than supported the action, which saw US, British and French forces fire more than 100 missiles at three Syrian government facilities.

Theresa May told a press conference at Downing Street yesterday: “While the full assessment of the strike is ongoing, we are confident of its success.”

But the new polling will be a blow for the prime minister, who threatened further strikes and prepared to justify the attack to MPs, whom she has so far denied a vote on the matter.

Moscow threatened “consequences”, but the political fallout was already clear with Western diplomats at the UN Security Council clashing with officials from Russia, which backs the Syrian regime of Bashar al-Assad.

Respondents to the BMG Research poll were still being questioned as RAF fighter jets were fuelling up in Cyprus for their mission on Friday morning.

The survey was carried out during days in which Ms May made the case for action in response to the alleged chemical weapons attack in Douma during a repeatedly broadcast interview, but it seems to have had little impact.

Asked to what extent people would back “UK forces conducting targeted air or missile strikes on Syrian government military targets”, just 28 per cent supported them, while 36 per cent opposed, 26 per cent neither opposed nor supported the strikes and 11 per cent did not know.

Syrian state TV shows footage of 'destroyed scientific research centre hit by air strike'

Interestingly, a no-fly zone over Syria policed by Western allies received far greater support, suggesting large numbers of people are convinced of a need to act.

Almost half of people asked (47 per cent) backed a no-fly zone to protect civilians in Syria’s civil war, just 11 per cent opposed, 9 per cent neither opposed nor supported and 12 per cent did not know.

There was an even split when asked if people would back some troops in Syria in non-combat roles, with a third backing the idea and a third against, but there was strong opposition to deploying soldiers in combat roles – with 48 per cent disapproving and just 19 per cent approving.

Britain used four Royal Air Force Tornados with Storm Shadow missiles in the air strikes, which they launched from the British RAF base in Akrotiri, Cyprus.

At the press conference hours later, Ms May warned the Assad regime that the UK and its allies would take further action if toxic weapons were used again.

Asked if there was more to come, she said: “The Syrian regime should be under no doubt of our resolve in relation to this matter of the use of chemical weapons.”

World reacts to Syria air strikes

But the BMG poll results could temper Ms May’s approach, as she now faces having to spend political capital to justify the attacks in the Commons – where some Tories and Labour leader Jeremy Corbyn were angry at being denied a vote in advance of the strikes.

The prime minister began on Saturday by publishing the elements of the government’s legal case for the operation, including that there had been convincing evidence of “extreme humanitarian distress”, no alternative but to act and an operation that was “proportionate to relieve humanitarian suffering”.

At the press conference earlier, Ms May said her cabinet had considered the legal advice and intelligence around the Douma incident before acting.

She went on: “And based on this advice we agreed that it was both right and legal to take military action, together with our closest allies, to alleviate further humanitarian suffering by degrading the Syrian regime’s chemical weapons capability and deterring their use.

“This was not about interfering in a civil war and it was not about regime change.”

That did not stop Mr Corbyn branding the action as “legally questionable”, before adding: “Bombs won’t save lives or bring about peace.

“Britain should be playing a leadership role to bring about a ceasefire in the conflict, not taking instructions from Washington and putting British military personnel in harm’s way.

Jeremy Corbyn condemns UK involvement in 'legally questionable' air strikes

“Theresa May should have sought parliamentary approval, not trailed after Donald Trump.”

The prime minister also prepared for a Commons statement on Monday in which she is likely to set out who was privy to the legal advice and the process which led to the decision to act – taken by her from her Chequers country retreat on Friday evening.

She, French president Emmanuel Macron and Mr Trump were sure of the success of the operation, with the US leader tweeting on Saturday: “A perfectly executed strike last night. Thank you to France and the United Kingdom for their wisdom and the power of their fine military. Could not have had a better result. Mission accomplished!”

The Pentagon reported that, despite claims in Syria, not a single one of the 105 missiles fired were intercepted by Assad forces, while Russian assets were not engaged.

Syrian president Bashar Al-Assad releases footage of him walking into work hours after air strike

US military officials confirmed that “deconfliction” lines had been used to minimise the chances of a clash between Russian and US planes, but said the mission destroying three chemical weapons facilities had set back Assad’s chemical weapons programme by years.

But Syrian state TV, which earlier in the day broadcast pictures of Mr Assad calmly arriving at work, called the attacks a “blatant violation of international law”.

The Russian embassy in the US said it had warned that such actions would “not be left without consequences”, adding that insulting President Vladimir Putin was “unacceptable and inadmissible”.

At around 3.30pm the UN Security Council brought diplomats from the world powers together after a Russian request for an emergency meeting following the strikes.