President Obama said tonight that evidence that chemical weapons were used in Syria would be a "game changer", while noting that intelligence assessments proving that such weapons had been used were still preliminary.
Mr Obama said that the US will be working with countries such as Jordan to get confirmation on use of chemical weapons in Syria, during Jordan's King Abdullah's visit to the country.
"Horrific as it is when mortars are being fired on civilians and people are being indiscriminately killed, to use potential weapons of mass destruction on civilian populations crosses another line with respect to international norms and international law," Mr Obama told reporters at the White House.
Earlier today, the Prime Minister described the alleged use of chemical weapons by the Syrian regime as "a war crime".
Speaking this morning on BBC Breakfast, the Prime Minister said that growing evidence of the use of chemical weapons was "very disturbing".
ITV News Middle East Correspondent John Ray's report, contains distressing images:
Labour leader Ed Miliband said the reports "would necessitate some kind of action" but has urged caution.
As a result, the UN launched an investigation today to conduct a "fact-finding mission" to look into all allegations of the possible use of chemical weapons in Syria. The team is reported to be deployed in 24 to 48 hours.