Syria submits further details of its chemical arms program UNITED NATIONS (Reuters) - Syria has given international experts additional details about its chemical weapons program that go beyond a September 21 declaration of its poison gas arsenal, the United Nations said on Friday. The team consists of experts from the Organization for the Prohibition of Chemical Weapons in The Hague, Netherlands, with help from U.N. personnel. Last week, the U.N. Security Council demanded the elimination of Syria's chemical arsenal. U.N. spokesman Martin Nesirky said the director-general of the organization, Ahmet Uzumcu, informed the agency's executive council that Syria has presented it with new details. "The additional submission is being reviewed by the Organization for the Prohibition of Chemical Weapons," Nesirky said. He said Uzumcu was expected to give OPCW member countries an update on Tuesday. He gave no details about the new information. Western diplomats in New York have said their countries' intelligence agencies are analyzing the declaration on Syria's chemical weapons program that Syrian President Bashar al-Assad's government submitted to the OPCW on September 21. The contents of Damascus' declaration have not been made public. According to declassified French intelligence, Syria's chemical arsenal includes more than 1,000 tonnes of chemical agents and precursor chemicals for the production of mustard gas and the nerve agents sarin and VX. Assad's government, threatened with U.S. airstrikes in retaliation for an August 21 sarin gas attack near Damascus that the United States says killed more than 1,400 people, agreed last month to accede to the Chemical Weapons Convention and abandon its chemical arsenal. On Thursday, the United Nations said the chemical experts have made "encouraging initial progress" and hoped to begin disabling equipment involved in Syria's chemical weapon process next week. The rebels and Syrian government blame each other for the deadly August 21 attack on a Damascus suburb. The United States and other Western countries say a report by U.N. investigators indirectly implicates government-allied forces. There was some optimism in Washington on the Syria situation. On Thursday, administration officials held a three-hour briefing for the Senate Armed Services Committee. Senator Carl Levin, the panel's chairman, said the officials who briefed the committee expressed confidence the chemical weapons plan would work, partly because Russia was pushing Assad to cooperate. "There is confidence that the chemical piece will work, because it's in everybody's interest to do it, including Russia's putting pressure on Assad," he told reporters. The United Nations has been notified of at least 14 chemical attacks since the 2 1/2-year civil war began. It estimates more than 100,000 people have died since the uprising against Assad began in March 2011. Russia, a staunch ally and arms supplier of Assad, also blames the rebels for the August 21 gas attack. The chemical weapons demolition plan and last week's Security Council resolution that made it legally binding were based on a deal reached last month in Geneva by Russian Foreign Minister Sergei Lavrov and U.S. Secretary of State John Kerry. Additional reporting by Patricia Zengerle; Editing by Doina Chiacu