But UN spokesman Martin Nesirky said no conclusion can be given on whether banned poison gas had been unleashed in Syria until laboratory tests are completed.
Nesirky also said it was "grotesque" to believe that the departure of UN weapons experts from Syria had opened up a possible window for a missile strike against President Bashar al-Assad's forces.
UN disarmament envoy Angela Kane briefed UN leader Ban Ki-moon on the mission in New York today.
Following criticism of the UN investigation mission, Nesirky said: "The United Nations mission is uniquely capable of establishing in an impartial and credible manner the facts of any use of chemical weapons."
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Kane told Ban that the UN inspectors were "able to conduct a wide range of fact finding activities," Nesirky told reporters.
The inspectors have taken the samples to The Hague and they will be moved to two laboratories in Europe, Nesirky said.
Ban said "whatever can be done to speed up the process is being done," according to Nesirky.
According to diplomats, Ban told ambassadors from Britain, France, the United States, China and Russia today that the team would need two weeks to complete a first analysis.
The United Nations still has more than 1,000 international and national staff in Syria and Nesirky said the world body was looking at which staff need to stay there.
"It's also an affront to the more 1,000 UN staff who are on the ground in Syria delivering humanitarian aid and who will continue to deliver critical aid," he said.