Labour Party leader Jeremy Corbyn has called the missile strikes "legally questionable"
The British Prime Minister is due to face a second emergency debate in the House of Commons on her decision to order missile strikes in Syria.
Theresa May yesterday faced MPs for the first time since green-lighting the military action in the early hours of Saturday morning.
Opposition leader Jeremy Corbyn has described the decision - taken without Parliamentary approval - as "legally questionable."
Noting that Mrs May bypassed Parliament and failed to get UN approval before joining the US and France in the coordinated action, he said the British Government must be held accountable to this Parliament and not to the whims of this US president."
He said Mrs May must publish the legal advice she received in full and outline what proof she has that the Syrian regime was behind the alleged chemical attack in Douma in the eastern Ghouta countryside outside Damascus on 7th April.
He agreed it was "highly likely" the Assad regime was behind it, but warned that other groups had carried out similar attacks and weapons inspectors must be allowed to continue their work.
The Organisation for the Prohibition of Chemical Weapons arrived in Damascus on Saturday ahead of its investigation into the attack.
It is due to begin its work in Douma tomorrow.
Yesterday, Mrs May defended her actions during a two hour and 45 minute session in the House of Commons.
She stressed that should not be able to have an effective veto over UK foreign policy by consistently blocking action against the Syrian regime at the UN Security Council.
Today, MPs will be asked to consider what role Parliament should have in approving any future UK military action.
Mr Corbyn said: "The Government's failure to seek - let alone obtain - parliamentary approval for these air strikes sets a precedent for potential and more dangerous future action not just in Syria, but other countries."
At least 70 people were killed in the attacks on Douma, however both the Syrian and Russian Governments have denied that chemicals were used or that the Assad regime was responsible.
Yesterday, Mrs May accused Russia and Syria of having so far prevented the OPCW from reaching the attack site.
She was boosted today when she won full support for military action against Syria from the G7 group of nations.
In a joint statement, the leaders of Canada, Germany, Italy and Japan backed the action taken by the UK, US and France.
We, the G7 Leaders, fully support all efforts by US, UK and France to degrade the Assad regime's ability to use chemical weapons and deter any future use. G7 statement: https://t.co/7gQz3Sz11E— Donald Tusk (@eucopresident) April 16, 2018
They said: "This response was limited, proportionate and necessary - and taken only after exhausting every possible diplomatic option to uphold the international norm against the use of chemical weapons.
"Use of chemical weapons is a breach of the Chemical Weapons Convention and constitutes a threat to international peace and security.
"The repeated and morally reprehensible use of chemical weapons by the Assad regime in the past has been confirmed by independent international investigators.
"We condemn this deliberate strategy of terrorizing local populations and forcing them into submission."
The second emergency debate in the House of Commons is due to get underway this afternoon.
With reporting from IRN ...