Russia on Friday said it had told the Syrian government to cooperate with UN experts after reports of a deadly chemical weapons attack outside Damascus, adding it was now up to rebels to allow access to the area. Foreign Minister Sergei Lavrov told US counterpart John Kerry in a phone call that immediately after the reports first emerged the \"Russian side called on the Syrian government to cooperate with the UN chemical experts,\" the foreign ministry said in a statement. \"It is now up to the opposition to ensure safe access for the mission to the site of the alleged incident,\" it added, saying both Lavrov and Kerry agreed on the need for an \"objective investigation\".