A boy, affected by what activists say is nerve gas, is treated at a hospital in the Duma neighbourhood of Damascus August 21, 2013. Syrian activists accused President Bashar al-Assad's forces of launching a nerve gas attack on rebel-held districts near Damascus on Wednesday that they said killed more than 200 people. There was no immediate comment from Syrian authorities, who have denied using chemical weapons during the country's two-year conflict, and have accused rebels of using them, which the rebels deny. REUTERS/Bassam Khabieh (SYRIA - Tags: POLITICS CIVIL UNREST CONFLICT)
ATTENTION EDITORS - VISUALS COVERAGE OF SCENES OF DEATH AND INJURY
A man sits in a hospital near two children who activists say were affected by nerve gas in the Ghouta region, in the Duma neighbourhood of Damascus August 21, 2013. Syrian activists accused President Bashar al-Assad's forces of launching a nerve gas attack on rebel-held districts near Damascus on Wednesday that they said killed more than 200 people. There was no immediate comment from Syrian authorities, who have denied using chemical weapons during the country's two-year conflict, and have accused rebels of using them, which the rebels deny. REUTERS/Bassam Khabieh (SYRIA - Tags: POLITICS CIVIL UNREST CONFLICT)