Russian Federation and Syria claim the attack was fabricated.
Theresa May has insisted the airstrikes, which targeted President Assad's chemical weapons facilities, were legal and "in Britain's national interest".
"We are confident in our own assessment that the Syrian regime was highly likely responsible for this attack and that its persistent pattern of behaviour meant that it was highly likely to continue using chemical weapons", she will say.
Jeremy Corbyn has forced a further Commons debate today on Syria by securing an emergency motion on whether Parliament should have the power to authorise military action in the future.
The UK Prime Minister is being grilled by lawmakers on Monday, April 16 and is expected to justify her decision to launch military attack on Syria without the parliament's approval. "And it was a decision that required the evaluation of intelligence and information, much of which was of a nature that could not be shared with parliament".
"In a sign of cynical disdain", the intervention took place on the same on the same day experts form the Organisation for the Prohibition of Chemical Weapons (OPCW) had just arrived to Syria to investigate the alleged chemical weapons attack.
Five percent of respondents said they thought there was probably no chemical weapons attack, while a further five percent said they thought "something else happened".
"She authorized military action with no mandate", said one Conservative lawmaker on condition of anonymity. "Nobody should be in any doubt of our resolve to ensure that we can not see a situation where the use of chemical weapons is normalised".
He added that the weekend attacks were legally questionable, telling May that she was accountable to the British parliament and not to the whims of U.S. President Donald Trump.
"Vladimir Putin, in particular, stressed that if such actions were committed in violation of the United Nations charter continue, then it will inevitably lead to chaos in global relations", the statement said.
"We can't go back to a world where the use of chemical weapons becomes normalized", May said.
He said chlorine has been used by "a number of parties in the conflict" in Syria as a weapon.
Legally, the British prime minister was not obliged to consult Parliament before ordering the military action, but the recent convention has been to do.
But she avoided answering questions on her future strategy for Syria, on whether parliament would be consulted on any further strikes and ignored demands by Corbyn for a War Powers Act to limit the government's power to launch military action.
Mr. Clarke called for the creation of a cross-party commission to deliberate on the role of lawmakers in authorizing military action.
"I think warnings are being issued", said Daniel Kenealy, a lecturer in public policy at Edinburgh University, adding that, lawmakers "are saying, 'Don't do this again'".
The Lib Dem leader, Vince Cable, said he regretted that the prime minister had not sought parliament's approval, but hinted his party would have given its backing, calling some of her arguments compelling.
Mr Corbyn said that if Britain wants to "get the moral high ground around the world" it must abide by worldwide law for taking military action.