BRUSSELS, Belgium—The international agency overseeing the disposal of Syria's chemical weapons said Tuesday that its inspectors were safe after they came under attack while investigating alleged chlorine gas use in a western province of the country.

The Organization for the Prohibition of Chemical Weapons neither confirmed nor denied a Syrian government statement that six of its inspectors had been kidnapped by antigovernment rebels while traveling by car to the site of the purported attack in Hama province, north of the capital...