It is "highly probably" chemical weapons have been used in Syria, a US intelligence official has said, echoing the words of a senior Israeli who also said chemical warfare in the country was "apparently clear."
Their comments came as Barack Obama landed in Israel for his first trip there as US president. Syria is likely to be one of the topics near the top of the agenda, as Israel is concerned the chemical weapons could be seized by Assad's ally Hezbollah or Al Qaeda rebels believed to be operating in the region.
Both Assad and the Syrian rebels accused each other of using chemical weapon after an attack on the northern village of Khan al-Assal on Tuesday.
However White House spokesperson Jay Carney said of the accusations made by Assad's government: "We are deeply sceptical of a regime that has lost all credibility and we would warn the regime of making these kind of charges as a pretext or cover for its use of chemical weapons.
"The President has made clear that the use of chemical weapons would be totally unacceptable and there will be consequences and the regime will be held accountable."
There have been unconfirmed reports that chemical weapons have been used in Syria throughout the two year conflict. On Tuesday night Mike Rogers, the head of the US House of Representative intelligence committee, told CNN that if chemical weapons had been used, the US was “morally obligated” to act.
“I have a high probability to believe that chemical weapons were used,” Mr Rogers told CNN. “We need that final verification, but given everything we know over the last year and a half, I would come to the conclusion that they are either positioned for use, and ready to do that, or in fact have been used.”
“If it takes a limited military strike to do that, I think we are morally obligated to do that if, in fact, they have crossed the president’s ‘red line’ of chemical weapons use,” Mr Rogers said.
His words echoed those of Israeli official Yuval Steinitz, the newly appointed minister of intelligence and strategic affairs, who told Army Radio "It is apparently clear that chemical weapons were used. The fact they apparently used chemical weapons against civilians needs to worry us and shows the urgency of taking care of the issue."
At least 25 people in the north of the country were killed in the attack, according to reports. Activists said the government fired the poisonous gas, hitting their own troops and civilians.