The convoy of UN investigation team leaves the Four Season hotel in Damascus, Syria, Aug. 30, 2013. The UN chemical investigation team will provide a preliminary report once they complete the probe work in Syria this weekend. The UN team, led by Swedish specialist Ake Sellstrom, was initially set to investigate the March 19 alleged chemical weapons attack on Khan al-Asal in the Aleppo region and two other sites of alleged chemical attacks. They later headed to the Damascus suburb of Ghouta, where chemical weapons were allegedly used on Aug. 21, to collect evidences. (Xinhua/Bassem Tellawi)

The convoy of UN investigation team leaves the Four Season hotel in Damascus, Syria, Aug. 30, 2013. The UN chemical investigation team will provide a preliminary report once they complete the probe work in Syria this weekend. The UN team, led by Swedish specialist Ake Sellstrom, was initially set to investigate the March 19 alleged chemical weapons attack on Khan al-Asal in the Aleppo region and two other sites of alleged chemical attacks. They later headed to the Damascus suburb of Ghouta, where chemical weapons were allegedly used on Aug. 21, to collect evidences. (Xinhua/Bassem Tellawi)