BEIRUT - Syria’s government and rebels Wednesday demanded an international investigation into a purported 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 he 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.

Along with its warnings about Assad, the West is just as concerned that rebel forces, including some linked to al-Qaida, could get their hands on Syria’s chemical weapons supplies.

Despite the importance, any clear confirmation of the nature of the attack that took place Tuesday in the northern village of Khan al-Assal, killing at least 31 people, is unlikely. Syria’s government seals off areas it controls to journalists and outside observers.

If a chemical attack were confirmed, it would be the first time a chemical weapon has been used in Syria’s war that has killed an estimated 70,000 people.

Syria’s U.N. Ambassador Bashar Jaafari told reporters at the United Nations on Wednesday that he had asked Secretary-General Ban Ki-moon to form “a specialized, independent and neutral technical mission to investigate the use by the terrorist groups operating in Syria of chemical weapons” in Khan al-Assal.

Jaafari called the attack “very serious and alarming and unacceptable and unethical.”

U.N. spokesman Martin Nesirky said he would have something to say “once we receive any formal request, which we have so far not received.” He said the secretary-general remains convinced that the use of chemical weapons by any party under any circumstances would constitute “an outrageous crime.”

Syria’s main opposition group also demanded an international investigation.

“All evidence now indicates that the Assad regime is using these weapons against its own people,” said the main Western-backed opposition group, the Syrian National Coalition.

“The Coalition demands a full international investigation, and asks for a delegation to be sent to inquire and visit the site,” the group said in a statement.

Obama has declared the use, deployment or transferof the weapons to be his “red line” for possible military intervention in the Arab country.

“When you start seeing weapons that can cause potential devastation and mass casualties and you let that genie out of the bottle, then you are looking at potentially even more horrific scenes than we’ve already seen in Syria,” Obama said in Jerusalem, “and the international community has to act on that information.”

Russia and Iran, Assad’s main allies, backed his regime’s charges.

Iranian Foreign Ministry spokesman Ramin Mehmanparast blamed “armed opposition groups,” calling use of chemical weapons “an inhuman act.”

Jordan’s king warned Wednesday that an extremist Islamic state could form on his border.

King Abdullah II said that in his view Assad was beyond rehabilitation and that it is only a matter of time before his authoritarian regime collapses.

“The most worrying factors in the Syrian conflict are the issues of chemical weapons, the steady flow or sudden surge in refugees and a jihadist state emerging out of the conflict,” the king said.

Jordan has set up a security cordon around a sprawling Syrian refugee camp in the country’s north to curb rising crime and lawlessness among its residents, a Jordanian official said Wednesday.

The cordon around the Zaatari camp, which is now home to more than 100,000 Syrians who fled the civilwar in their country, will be enforced by members of Jordan’s desert patrol force, said Anmar Hmoud.

In fighting Wednesday, activists reported clashes in the Quneitra region on the ceasefire line between Syria and Israel in the Golan Heights.

The Britain-based Syrian Observatory for Human Rights said rebels seized control of parts of villages a few miles from the cease-fire line after fierce fighting with regime forces.

It said seven people, including three children, were killed by the government shelling villages.

Also Wednesday, Assad made a rare public appearance, visiting a fine-arts school in Damascus and meeting the parents of students who were killed in the civil war, state TV reported.

Photos published by the Syrian state media showed Assad shaking hands and listening closely to people who were said to be parents of war victims. It was his first appearance outside his palace since January, when he delivered a speech.

“All of Syria is wounded, and there is no one who hasn’t lost a relative, a brother, a father or a mother,” Assad said, according to the official news agency SANA.

“However, all that is happening cannot make us weak, and the battle is a battle of will and steadfastness,” he added.

Information for this article was contributed by Bassem Mroue, Ben Hubbard, Edith M. Lederer, Donna Cassata, Jamal Halaby and Dale Gavlak of The Associated Press.

Front Section, Pages 6 on 03/21/2013