UNITED NATIONS (AP) ― Syria asked U.N. Secretary-General Ban Ki-moon on Wednesday to appoint an independent mission to investigate an alleged chemical weapons attack that the regime has blamed on rebels in northern Syria.

The rebels have denied the government claim and blamed regime forces for Tuesday’s missile attack on Khan al-Assal village in northern Aleppo province. The Syrian National Coalition, the main opposition group, also demanded an international investigation Wednesday.

France’s U.N. Ambassador Gerard Araud, who raised the issue in the U.N. Security Council late Wednesday, said the Syrian National Coalition has alleged that there was a second chemical weapons attack Tuesday in the Damascus area and it should be investigated.

Russia’s U.N. Ambassador Vitaly Churkin, whose country has close ties to the Syrian government, accused France and its Western supporters of “launching propaganda balloons” and trying to delay an investigation of the Aleppo incident.

Syria’s U.N. Ambassador Bashar Ja’afari said he was “not aware of a second attack.” He said the allegation was “set up to torpedo the investigation of the real use of chemical weapons” in Aleppo.

Even though there was no Security Council agreement, the French and British said they plan to send a letter to the secretary-general asking him to investigate both alleged attacks, signed by as many of the 15 council members as possible.

The dispute reflected the deep divisions that have prevented the Security Council from taking any action to end Syria’s violence.

Ja’afari told reporters Wednesday morning that the Syrian government asked the secretary-general “to form a specialized, independent and neutral technical mission to investigate the use by the terrorist groups operating in Syria of chemical weapons yesterday against civilians in the town of Khan al-Assal in Aleppo.”

U.N. spokesman Martin Nesirky said Ban has received a written request from Syrian authorities and it is being studied.

The U.S. ambassador to Syria, Robert Ford, said Wednesday the Obama administration has no evidence so far to support Syria’s accusations, or that a chemical weapons attack occurred at all.

If confirmed, the attack would be the first time a chemical weapon was used in Syria’s two-year-old civil war.

The Syrian government, which refers to the rebels as “terrorists,” said 31 people were killed and more than 100 wounded in the missile attack in Aleppo.

Ja’afari called the attack “very serious and alarming and unacceptable and unethical.” He said Syria asked the secretary-general for assistance “in a sign of good faith, good will, good intentions” to the international community and the Syrian people.

He reiterated earlier that the secretary-general remains convinced that the use of chemical weapons by any party under any circumstances would constitute “an outrageous crime.”

Ban spoke to Ahmet Uzumcu, director general of the Organization for the Prohibition of Chemical Weapons, on Tuesday and both expressed deep concern at the allegations of chemical weapons use. He said the organization is monitoring the situation.

Ja’afari recalled that Syria sent a letter to Ban and the U.N. Security Council in December warning that rebel groups might use chemical weapons and then blame the government.

“The Syrian government, if it has such weapons, will never use it against its own population,” Ja’afari said.

He said that Syria had proposed a Security Council resolution in 2003 when it was a council member that would have required the Mideast to be free of all weapons of mass destruction. He said it was blocked by the threatened veto of an “influential member,” an apparent reference to the United States, Israel’s closest ally.

Ja’afari said Syria is a party to most U.N. conventions dealing with weapons of mass destruction, but it is not a party to the chemical weapons convention.