BEIRUT – Syria's government and rebels on Wednesday both demanded an international investigation into an alleged chemical weapons attack, as the country's feared arsenal became the latest propaganda tool in the 2-year-old civil war.

President Barack Obama said the United States is investigating whether chemical weapons have been deployed in Syria, but noted that he is "deeply skeptical" of claims by President Bashar Assad's regime that rebel forces were behind such an attack.

"Once we establish the facts, I have made clear that the use of chemical weapons is a game changer," Obama said in a news conference with Israeli Prime Minister Benjamin Netanyahu in Jerusalem.