Britain, France and the United States called Wednesday for a United Nations inquiry into accusations by the Syrian government and the opposition of chemical weapons attacks, diplomats said, according to AFP.
Russia, President Bashar al-Assad's last major ally, insisted however at a UN Security Council meeting that only the government's allegations should be investigated.
Syria has asked the United Nations to order an "independent" investigation into its claim that opposition rebels used chemical weapons in an attack near Aleppo on Tuesday.
UN spokesman Martin Nesirky said a written request has been from the Damascus government "and it is being studied."
The opposition has said however that the government used chemical weapons in the Aleppo attack and another near Damascus.
Divisions over the two year-old Syria conflict again erupted at a Security Council meeting where France raised the allegations.
French UN ambassador Gerard Araud said there was no proof yet of the use of chemical weapons by any side.
He told reporters that a majority of the 15 members of the council had wanted to send a letter to UN Secretary General Ban Ki-Moon calling for an investigation into "all allegations of the use of chemical weapons."
Britain and the United States were among countries to back the proposal, according to AFP.
"The facts need to be clarified," said Britain's deputy UN ambassador Philip Parham.
Russia's UN ambassador Vitaly Churkin said the western initiative was an attempt "to delay" any investigation into claims of weapons use in Aleppo.
"Instead of launching those propaganda balloons I think that it’s much better to get our focus right and I hope this is what the secretary general is doing," Churkin told reporters.
The chairman of the U.S. House Intelligence Committee, Rep. Mike Rogers, said on Tuesday 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.
An Israeli source was more firm on the matter, confirming that chemical weapons were used in attacks on the cities of Aleppo and Damascus.
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.”