Ban said his senior advisers are setting up an investigation in consultation with the Organization for the Prohibition of Chemical Weapons and the World Health Organization. He said issues to be decided include the overall mandate, the composition, and operational conditions, including security.
The investigation will start "as soon as practically possible," Ban said, but "will not happen overnight."
Nesirky said there are "technical reasons for being on the ground sooner rather than later." He said the OPCW and WHO have the necessary technical expertise.
The OPCW, which oversees the Chemical Weapons Convention, said in a statement that it was ready to work closely with the U.N. on establishing and conducting the mission.
"While allegations of this nature are not new to conflict situations, they are nonetheless serious, especially in the context of Syria which is not a state party to the Chemical Weapons Convention," the OPCW said. "This remains a matter of serious concern."
Ban said he would emphasize in a letter to the Syrian government that full cooperation from all parties and "unfettered access" would be essential to the investigation. The U.N. chief said he has spoken out repeatedly on the Syrian government's responsibility to secure any chemical weapons and has sent two letters to Assad "to remind him of this solemn duty."
"It is my hope that the mission would contribute to ensuring the safety and security of chemical weapons stockpiles in Syria," he said.
With more than 70,000 people killed and no end to the violence in sight, Ban said "the military solution in Syria is leading to the dissolution of Syria."
He called on the deeply divided region and international community to find unity and support efforts by the joint U.N.-Arab League envoy Lakhdar Brahimi to help the Syrian people reach a political solution.
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