By Anthony DeutschTHE HAGUE (Reuters) - Syria must disclose documents about its chemical weapons program and grant full access to inspectors if it wants to convince world powers it has destroyed its entire toxic stockpile, U.N.. disarmament chief Angela Kane said on Tuesday.The issue of Syria's destruction of its chemical weapons stockpile dominated discussions at a conference of the Organisation for the Prohibition of Chemical Weapons (OPCW) in The Hague on Tuesday.The effort was launched after a sarin gas attack on Aug. 21 last year during the Syrian civil war that killed hundreds of civilians in the Damascus suburb of Ghouta.President Bashar al Assad's government and rebel forces blamed each other for the strike. Damascus joined the OPCW, without admitting responsibility for the attack, after the United States threatened military intervention.The government declared 1,300 metric tonnes of chemical weapons and dozens of production and storage sites to the OPCW last year but has not provided written documentation to support the reporting of its weapons of mass destruction.As part of a logistical operation involving more than a dozen countries, Syria handed over the chemical weapons, 98 percent of which have been destroyed abroad, largely on a converted U.S. ship, the MV Cape Ray.But several powers, including the United States, Britain, France and Germany, have expressed concerns that the entire program has not been revealed."It is up to Syria to be transparent and to come forward, either with documentation, or access to people (involved in the program), or sites," Kane told Reuters.Geoffrey Adams, Britain's representative to the OPCW, expressed the views of many governments in comments to conference delegates about efforts by the agency to compile a complete picture of the program."We urge Syria to use the opportunity of the team's next visit to Damascus to provide credible evidence and documentation to support its assurances that it has fully abandoned its chemical weapons program," he said.A fact-finding mission is investigating illegal chlorine bombs, the use of which the team concluded in an initial report has been "systematic".Kane added: "What we are talking about is gaining confidence in whatever has been declared...that they are full filling all the requirements of the convention.(Reporting By Anthony Deutsch; Editing by Angus MacSwan)Join the conversation about this story Click here to read full news..