Members of the Syrian opposition claimed on Sunday night that President Bashar Al-Assad’s forces fired chemical weapons from multiple rocket launchers at rebels surrounding an army base in the town of Adra, on the outskirts of Damascus.
Two opposition fighters were killed and 23 were wounded in the attack, the opposition said.
"Doctors are describing the chemical weapon used as phosphorus that hits the nervous system and causes imbalance and loss of consciousness,” an opposition activist said.
He added that the two fighters who were killed had been “very close to where the rockets exploded and they died swiftly. The rest are being treated with Atropine.”
There was no independent confirmation of the attack, which came less than a week after an attack on Aleppo killed nearly 30 people.
Following the Aleppo attack last Tuesday, the Syrian government accused opposition rebels of using chemical weapons. The opposition, in turn, said the government staged the attack and also used banned chemical weapons in another incident near Damascus.
The chairman of the U.S. House Intelligence Committee, Rep. Mike Rogers, later said that there is a "high probability" that Syria used chemical weapons in the ongoing civil war.
"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," he told CNN.
Last Wednesday, Minister of Intelligence and Strategic Affairs Yuval Steinitz said in an interview that it is “apparently clear” that either Syrian rebels or the Damascus regime have used chemical weapons in the country's two-year civil war.
"This is very concerning for us and we must deal with it urgently," said Steinitz.
U.S. President Barack Obama, however, was more careful when asked about the situation during a news conference in Jerusalem with Prime Minister Binyamin Netanyahu.
Obama indicated that not all the facts on what happened in Syria on Tuesday were clear, saying, “With respect to chemical weapons, we intend to investigate thoroughly exactly what happened. Obviously in Syria right now you've got a war zone, you have information that's filtered out, but we have to make sure that we know exactly what happened, what was the nature of the incident, what can we documented, what can be proved.”
The United Nations has said it will investigate whether chemical weapons have been used in the Syria conflict.
A British report published Sunday states that chemical weapons were not used in attacks in Syria last week. The report’s authors said that the attackers used highly concentrated tear gas, but did not use nerve gas or other unconventional weapons as had been reported.
Meanwhile on Sunday, Syrian jihadist rebel forces seized a 25-kilometer (15 mile) buffer zone stretching from the Jordanian border to the Golan Heights.
On Sunday, Israel warned Syria the IDF would retaliate by destroying the source of any gunfire directed across its northern border, regardless of who fired. The warning came after two separate attacks within a 12 hour period aimed at IDF military vehicles, both of which hit and damaged the jeeps but did not injure any Israeli soldiers.