The AFP news agency quoted French government spokesman Benjamin Griveaux as saying on Tuesday that "if a red line had been crossed, there will be a response", adding that intelligence shared by the two leaders "in theory confirms the use of chemical weapons".
The White House announced Tuesday President Donald Trump would not make his scheduled trip to Latin America this week so he could remain in the U.S.to oversee the "American response to Syria and to monitor developments around the world".More news: Rome goes insane over miracle comeback in Roma vs Barcelona
Prime Minister Theresa May has called government ministers to a Thursday cabinet meeting on Syria, which media reports said was likely to lead to London joining in a military response to a suspected chemical attack in Syria.
Russian Federation first vetoed a US-drafted text to create a mechanism that would have the authority to assign blame for chemical attacks in the war-torn country.
The escalating war of words follows the UN Security Council's failure this week to pass a resolution outlining steps to investigate the chemical attack.
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Following the failure of both the Russian and American proposals, Nebenzya stated that if the United States "took the decision to carry out an illegal military adventure - and I do hope you come to your senses - well, then you will have to bear responsibility for it yourselves".
"We believe the gas used was chlorine and another kind of gas", said Mohammed Marhoum, a medical worker.
The United States, backed by Britain and France, has said it is ready to act with or without support from the United Nations, where the Security Council was to vote as early as Tuesday on rival U.S. and Russian proposals to probe chemical attacks in Syria.More news: Pep Guardiola "delighted" with Manchester City players