It follows a wave of strikes by the US, UK and France against alleged chemical weapons facilities in Syria.
The Times reports that "the largest USA air and naval strike force since the 2003 Iraq war" is now heading towards Syria, and that US-led strikes are expected to begin "within the next three days". On Thursday, however, he tweeted: "Never said when an attack on Syria would take place".
Officials also said that the US has compiled intelligence from the USA and other countries, including images, that indicate the Syrian government was behind the weekend attack.
Mrs May is expected to ask her cabinet to approve a form of British participation in action led by France and the United States, aimed at Syrian President Bashar al Assad's chemical weapons infrastructure.
Since Saturday, when images of ashen toddlers struggling for breath emerged from Douma - the main city in the Eastern Ghouta enclave near Damascus that has been a crucible of revolt against Bashar Al-Assad's regime - there has been a sustained military buildup in the eastern Mediterranean.
Britain's Ministry of Defense refused to comment on reports that Royal Navy submarines armed with cruise missiles have been dispatched into range of Syria.
The UN Security Council, tasked with maintaining worldwide peace and security, has been riven, with Moscow virulently denying the Douma attack took place, or postulating that it was carried out by rebels. "We have the proof that chemical weapons - at least chlorine gas - were used by Assad's regime", Macron told France's TF1 television.
Britain's Prime Minister Theresa May walks out of 10 Downing Street to greet Portugal's Prime Minister Antonio Costa in London Thomson Reuters LONDON (Reuters) - British Prime Minister Theresa May summoned her senior ministers to a special cabinet meeting on Thursday to discuss joining the United States and France in possible military action against Syria after a suspected poison gas attack on civilians.
Amid the talk of military action, the Kremlin, a close ally of Assad, countered that more "serious approaches" were needed to combat the crisis.
There is no guarantee lawmakers would rubber-stamp a decision for military strikes.
National security experts anxious about whether strikes would actually serve to deter Assad.
Laurence Geai/SIPA/NewscomPresident Trump says there will be a "big price to pay" for the horrific chemical weapons attack reported in the rebel-held area of Eastern Ghouta, Syria. The fact-finding mission of the OPCW is to start their work in Douma on Saturday.