Besides weapons locations declared by Damascus as part of a deal to head off threatened military strikes, inspectors will also be able to visit "any other site identified by a State Party as having been involved in the Syrian chemical weapons programme," says the draft document seen by AFP.
The draft says however that such matters could be resolved through "consultations and cooperation" and that the OPCW's Director General Ahmet Uzumcu can deem claims of hidden chemical weapons as "unwarranted".
Syria agreed to give up its chemical weapons as part of a US-Russian agreement made earlier this month, worked out as Washington threatened military action in response to an August 21 chemical weapons attack outside Damascus.
In cases of non-compliance with the plan, which sees all Syrian chemical weapons and facilities destroyed by mid-2014, the OPCW will discuss the allegation and "bring the issue or matter... Directly to the attention of the United Nations General Assembly and the United Nations Security Council."
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All Syrian chemical weapons facilities must be inspected no later than 30 days after the document is adopted.
The OPCW's Executive Council is to decide on "intermediate destruction milestones" by November 15, it said, calling also on Syria to provide "immediate and unfettered right to inspect any and all sites."
The OPCW shall "as soon as possible and in any case not later than October 1 initiate inspections in the Syrian Arab Republic pursuant to this decision."
The OPCW meeting comes after the United States and Russia agreed a draft UN Security Council resolution on Syria's chemical weapons on Thursday, breaking a prolonged deadlock.
The 15-member Security Council is to vote on the resolution on Friday, after the OPCW meeting.