Syrian President Bashar al-Assad's government and the opposition demanded independent investigations Wednesday into countering accusations of the use of chemical weapons, allegations that prompted most members of the U.N. Security Council to call for a probe.
The demands, made in writing to the United Nations, came a day after the government and the rebels accused one another of using chemical weapons in fighting in the flashpoint province of Aleppo and a rural suburb of the Syrian capital of Damascus.
Even as both sides accused the other of using such weapons, the U.S. ambassador to Syria and other officials said there was no evidence to substantiate the reports.
"So far, we have no evidence to substantiate the reports that chemical weapons were used yesterday," Ambassador Robert Ford told the House Foreign Affairs Committee.
"But I want to underline that we're looking very carefully at these reports. We are consulting with partners in the region and in the international community."
Ford, who was pulled from Syria when the United States closed its embassy in Damascus more than a year ago, said he was "skeptical" of Russian reports that the rebel Free Syrian Army had used chemical weapons.
Competing calls for investigations
Throughout the civil war, which began in 2011, it has been difficult for the international community to determine the validity of claims by both sides of violence and casualties because access to the country has been severely restricted by the Syrian government.
Even so, the United Nations confirmed Wednesday it was studying a written request received from Syrian government officials, who were calling for a neutral party to investigate their claim.
A majority of the members of the U.N. Security Council plan to send a letter to Secretary-General Ban Ki-moon to request an inquiry to "shed light" over the reports, said Gerard Araud, the French ambassador to the United Nations. He made the comments after Wednesday's closed-door meeting of the Security Council.
The letter asks Ban to conduct a "swift, thorough and impartial" investigation, Philip Parham, the UK's deputy ambassador to the United Nations, said.
Parham described the Syrian government's demand as a request for a narrow investigation, looking into only one alleged incident.
"The way in which they have framed the request prejudges the outcome of the investigation by alleging it's the opposition that is responsible for that case of use of chemical weapons," he said.
The Security Council is calling for a broader investigation.
The rebels' coalition government, meanwhile, demanded an international investigation and called for a delegation to visit the sites of the alleged attacks.
Military analysts believe the Syrian government may have one of the largest stockpiles of chemical weapons in the world. Specifically, the supply is believed to include sarin, mustard and VX gases, which are banned under international law. Syria has denied the allegation.
The use of chemical and biological weapons are banned under the Chemical Weapons Convention. Syria is not one of the 188 signatories to the convention, which bans the production, stockpiling and use of chemical weapons.
In recent months, reports have repeatedly surfaced that Syrian forces moved some of the chemical weapons inventories possibly because of deteriorating security in the country, raising fears the stockpile could fall into the hands of al Qaeda-linked groups working with the opposition should al-Assad's government fall.
As a result, the United States has been talking with neighboring countries about the steps needed to secure the weapons stockpile should al-Assad be forced from office.
Meanwhile, U.S. President Barack Obama on Wednesday reiterated his warning to Syria's government that it would be held accountable for the use of chemical weapons "or their transfer to terrorists."
"We intend to investigate thoroughly exactly what happened," Obama told reporters during a joint news conference in Jerusalem with Israeli Prime Minister Benjamin Netanyahu.
The president said he was "deeply skeptical" of Syrian government claims that the opposition used chemical weapons.
Obama has previously said Syria's use of chemical weapons would cross a "red line."
"We have been very clear to the Assad regime -- but also to other players on the ground -- that a red line for us is, we start seeing a whole bunch of chemical weapons moving around or being utilized," he told reporters. "That would change my calculus; that would change my equation."
Intelligence agencies pore over the evidence