By Anthony Deutsch and Dominic Evans
AMSTERDAM/BEIRUT (Reuters) - Safety concerns have prevented inspectors from a global chemical weapons watchdog from reaching two of the 23 sites declared by Syria as part of an agreement to destroy its toxic arsenal, the organization said on Monday.
The Organisation for Prohibition of Chemical Weapons (OPCW) had verified 21 sites up to October 27, the deadline agreed as part of Syria's destruction program.
"The two remaining sites have not been visited due to security reasons," the OPCW, which won the Nobel Peace prize this month, said in a statement.
Visiting the sites has posed serious dangers for the inspectors with fighting continuing to rage in a 2-1/2 year civil war that has killed more than 100,000 people.
The location of the two remaining sites was not provided by the OPCW, but an official speaking on condition of anonymity played down their significance, saying "one is empty and the other is also otherwise not that important".
At least one site linked to Syria's chemical weapons program - near the northern town of Safira - is close to current battles between rebel fighters and forces loyal to President Bashar al-Assad.
"Efforts by the Joint Mission (with the UN) to ensure the conditions necessary for safe access to those sites will continue," the statement said.
Under a Russian-American brokered deal, Damascus agreed to destroy all its chemical weapons after Washington threatened to use force in response to the killing of hundreds of people in a sarin chemical attack on the outskirts of Damascus on August 21.
The United States and its allies blamed Assad's forces for the attack and several earlier incidents. The Syrian president has rejected the charge, blaming rebel brigades.
By another deadline next Friday, Syria must have rendered unusable all production and chemical weapons filling facilities. By mid-2014 it must have destroyed its entire stockpile of chemical weapons.
SYRIA'S CHEMICAL ARSENAL
Those ambitious targets are likely to be difficult to achieve, particularly as diplomatic efforts to curb the violence have made little headway. But the OPCW says they are achievable.
In a report covering the initial stages of work to eliminate Syria's chemical stockpile, the organisation said Damascus had submitted detailed information on its weapons stockpile as well as production and storage facilities.
The October 25-dated report, a copy of which was obtained by Reuters, said Syria listed 1,000 tonnes of chemical weapons and another 290 tonnes of toxic or chemical agents, along with 1,230 unfilled chemical munitions.
Syrian authorities had also reported finding "two cylinders not belonging to them, which are believed to contain chemical weapons", the report said. It did not say whether Syrian officials, who accuse rebel fighters of also having chemical weapon capacity, had handed over the two cylinders.
Syria's 23 chemical weapons sites included 41 facilities, including 18 production units, 12 storage units and eight mobile filling units as well as three other related facilities, the report said.
Assessing Syria's cooperation so far, the report said that the findings of inspections carried out in the last three weeks corroborated the information provided by authorities, and said they had extended "the necessary cooperation to the OPCW team".
The OPCW, established to enforce the 1997 Chemical Weapons Convention has around 500 staff and an annual budget of under $100 million. It will need significantly more resources to finish the inspection and destruction of weapons, experts say.
(Editing by Barry Moody)