The United Nations will investigate whether chemical weapons have been used in the Syria conflict, UN Secretary General Ban Ki-Moon announced on Thursday, according to AFP.
Ban said the "difficult mission" would focus on a Syrian government allegation that opposition rebels used chemical weapons in an attack this week.
France, Britain and the United States called on Ban to widen the inquiry to include accusations made against President Bashar al-Assad's forces.
The Syrian government accuses opposition rebels of using chemical weapons in Khan al-Assal near Aleppo on Tuesday and says that more than 30 people died. The opposition said the government staged the attack and also used banned chemical weapons in another incident near Damascus.
"I have decided to conduct a United Nations investigation into the possible use of chemical weapons in Syria," Ban told reporters, according to AFP. He said it would start "as soon as is practically possible."
The UN is working with the Organization for the Prohibition of Chemical Weapons (OPCW), which oversees the Chemical Weapons Convention, and the World Health Organization to set up the inquiry.
Ban said the mission would "look into the specific incident" raised by the Syrian government in a letter to the UN on Wednesday.
"I am, of course, aware that there are other allegations of similar cases involving the reported use of chemical weapons," he added.
Britain and France called for a wider inquiry that includes accusations that chemical weapons were also used at Ataybah near Damascus and another incident at Homs on December 23.
"We judge it essential that all the pertinent facts concerning these allegations are swiftly investigated," said a letter sent by the French and British missions to the UN leader. It called for "an urgent investigation into all allegations".
UN spokesman Martin Nesirky said the French-British letter had been received. "The secretary general will review this suggestion as the mandate for the UN investigation is developed," he told reporters, according to AFP.
U.S. ambassador Susan Rice said the United States also "supports an investigation that pursues any and all credible allegations of the possible use of chemical weapons in Syria."
Russia's UN ambassador Vitaly Churkin welcomed the announcement made by Ban, calling it "a very good, courageous decision."
Russia and China have blocked three western-proposed UN resolutions that would have stepped up pressure on Assad over the conflict in which the UN says well over 70,000 people have died.
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.
On 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 his news conference 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.”