DAMASCUS, Syria — A convoy of chemical weapons inspectors came under attack Tuesday while traveling to the site of a suspected chlorine gas attack in Syria, but all staff members were safe, the international watchdog agency said.

The Organization for the Prohibition of Chemical Weapons has been working with the United Nations to oversee the destruction of the Syrian government’s stockpiles since September 2013, when President Bashar Assad’s administration acknowledged it has chemical weapons and agreed to give them up to avoid the threat of U.S. military strikes.

Syria has since destroyed or handed over more than 90 percent of the weapons and toxic chemicals it has formally declared. Its sole remaining declared stockpile has been packaged for shipment out of the country to meet a June 30 deadline for destruction.

However, last month allegations surfaced that chlorine gas has been used as a weapon in fighting between the government and rebels. Chlorine is not banned under chemical weapons conventions, and it was not part of Syria’s disclosures. However, using any toxic material in warfare violates chemical weapons treaties and international law.

The circumstances of Tuesday’s attack were unclear. Syria’s Foreign Ministry initially reported that 11 people, including six members of a U.N. fact-finding mission and their Syrian drivers, had been abducted by rebels fighting to topple Assad’s regime. But the OPCW issued a statement shortly afterward saying a convoy had come under attack but “all team members are safe and well and are travelling back to the operating base.”