"If we can ensure cooperation by all parties, and if some temporary ceasefires could be established in order to permit our experts to work in a permissive environment, I think the targets could be reached," Organization for the Prohibition of Chemical Weapons (OPCW) head Ahmet Uzumcu said in The Hague on Wednesday.

Uzumcu said that Syrian officials had been "quite cooperative" in the early stages of the destruction of Syria's chemical weapons arsenal.

Syria submitted a declaration of its chemical weapons arsenal to the OPCW last month.

"Much depends on the situation on the ground, that's why we have urged all parties in Syria to be cooperative," Uzumcu said. "The elimination is in the interest of all."

Inspectors have already visited one chemical site in Syria and are visiting another on Wednesday, with some weapons already destroyed. "There are 20 sites to be visited in the coming weeks," Uzumcu said.

Speaking at the same press conference, Uzumcu's political advisor Malik Ellahi said "at the moment there are certain sites that are located in areas which are dangerous."

Ellahi added that most sites to be inspected at this stage were in Syrian government-controlled areas.

Some 19 OPCW arms experts and 16 UN logistics and security personnel are in Syria and have started to destroy weapons production facilities, with footage of their work broadcast on Syrian television.

UN chief Ban Ki-moon has warned that the weapons inspectors face unprecedented danger, saying it would take 100 foreign experts to complete "an operation the likes of which, quite simply, has never been tried before".

Under a Russian-US deal brokered in September, Syria must render useless all production facilities and weapons filling equipment by November. Its entire chemical weapons program must be destroyed by June 30, 2014.

NTJ/NJF