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.
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".
The plan embodies the Russian-US chemical arms deal for Syria, reached by Sergei Lavrov and John Kerry in Geneva.
The OPCW 41-member Executive Council will meet late on Friday to discuss its chemical weapons plan for Syria. After that, at 0:00 GMT Saturday, the UN Security Council will debate a draft UN resolution specifying possible sanctions for violations of the chemical weapons ban in Syria.
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."
Syria is required to supply further details on its chemical weapons stockpile within seven days of the OPCW draft being adopted, it said.
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."
Syria is also required to designate a liaison official for the OPCW and "provide him or her with the authority necessary to ensure that this decision is fully implemented."
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.
The Organization for the Prohibition of Chemical Weapons Executive Council is expected to debate a draft decision on plans to destroy Syria's chemical weapons stockpiles at its session.
The session will begin at the organization's headquarters in The Hague at 10:00 p.m. local time on Friday, the OPCW press service said.
The UN Security Council will vote late Friday on a draft resolution stipulating the destruction of Syria’s chemical weapons, the French permanent mission at the UN reports on its Twitter page.
“The UN Security Council has scheduled a vote on the Syrian chemical weapons resolution for 8 pm on Friday (0:00 GMT, 01:00 BST Saturday)”, the report says.
Syria's stockpile of chemical agents is largely "unweaponized" and could be eradicated more quickly than initially thought, the Washington Post reported Thursday citing a confidential US and Russian assessment.
The report said American and Russian officials now believe Syria's entire arsenal could be dismantled within a nine-month timeframe, and that the unweaponized state of the chemicals made it less likely they could be hidden or seized by terrorist organizations.
The Post cited two unnamed people who had been briefed on the analysis.
The report came as the United States and Russia agreed a landmark draft UN Security Council resolution on destroying Syria's chemical weapons.
The resolution would be the first passed by the 15-member council since the start of the Syrian conflict in March 2011.
Diplomats said the resolution allows for the council to decide on sanctions against Syria's President Bashar al-Assad at a later date if a breach of a Russia-US disarmament plan is reported.
The Post reported that in private briefings to weapons experts, analysts had estimated Syria possesses more than 1,000 metric tons of chemical weapons, including 300 metric tons of sulfur mustard.
However, the remainder of the stockpile was made up of chemical precursors to nerve agents that were "unweaponized" and in "liquid bulk" form and therefore easier to destroy.
The report said two chemical precursors for sarin nerve gas needed to be blended using special equipment before being loaded into rockets or artillery shells.
Voice of Russia, AFP, Washington Post, RIA