"The number of sites visited where inspection activities have been conducted has increased to 14," the Organisation for the Prohibition of Chemical Weapons said in a statement.
Damascus has identified a total of 20 sites but the OPCW has not provided an exact number, saying only that "more than 20 sites" are affected by the ongoing inspection.
The Hague-based organisation said yesterday that it had completed "nearly 50 per cent" of the inspection of Syria's chemical arsenal, which has to be destroyed by mid-2014. A day earlier, it had said that 11 sites had already been inspected.
The organisation, which last week was awarded the Nobel Peace Prize, and the United Nations currently have about 60 experts working in Syria to eradicate chemical weapons.
The OPCW last month accepted President Bashar al-Assad's application to join the Chemical Weapons Convention, in a bid to stave off a possible Western military strike.
Syria formally joined the convention on Monday.
So far Syria has won rare praise for its cooperation with the inspectors, but the UN has stressed that key deadlines in the destruction of Syria's chemical weapons should be met.
Meanwhile, the Dutch official named by the UN to head the dangerous mission in Syria "is scheduled to visit The Hague soon for briefings and discussions," the OPCW said, declining to give exact dates.
Sigrid Kaag, a UN assistant secretary-general who speaks fluent Arabic and has wide Middle East experience was appointed on Wednesday to head the mission.
