U.N. Secretary-General Ban Ki-moon appointed Swedish chemical weapons expert Ake Sellstrom to lead a fact-finding mission to investigate allegations of the use of chemical weapons in Syria. Sellstrom was a member of a U.N. weapons inspection team in Iraq.
Sellstrom said there's much preparatory work to do but the mission should get under way next week.
"The mission will happen in a week's time or so," he told U.N. Radio. "We also have to rely on the security situation to allow us to do the mission."
Ban said the mission was in response to a formal complaint issued by the Syrian government about possible chemical weapons use by rebel forces in Aleppo. He said he was aware of other reports apart from rebel use, however.
U.N. spokesman Martin Nesirky said the investigation had a very narrow focus.
"It is not the role of this mission to apportion responsibility or blame," he said. "It's not a criminal investigation. It's looking at whether chemical weapons were used, and not by whom."
Syrian civil war is in its third year. The United Nations estimates at least 70,000 people have died as a result of war and more than 1 million people have been displaced.