A Syrian rebel commander said a team from the world's chemical weapons watchdog investigating an alleged chlorine attack against rebel-held Kafr Zita managed to visit the town Tuesday, hours after coming under attack.

Inspectors overseeing the dismantling of Syria's weapons program had been forced to return to their base after their convoy was attacked, but all were safe, the Organisation for the Prohibition of Chemical Weapons (OPCW) said.

The Syrian foreign ministry accused rebels of kidnapping the team, while opposition activists said the regime planted an explosive device under one of the vehicles to try to stop investigators from investigating the alleged use of chlorine.

Then, on Tuesday afternoon, the OPCW team "arrived in Kafr Zita in the company of the Syrian Saiqa force, which is part of the (rebel) Free Syrian Army," said Colonel Mohammad al-Ali, general commander of the faction.

Amateur video distributed by activists showed two white UN vehicles parked in what appeared to be Kafr Zita, and opposition fighters meeting with a member of the delegation.

The visit to Kafr Zita was aimed at investigating allegations that Syrian government forces unleashed a chlorine attack on the town last month.

If confirmed, the attack would be in breach of Syria's commitments under the Chemical Weapons Convention.

The Syrian government signed the convention last year as part of a Russian- and US-brokered deal under which it pledged to destroy all of its chemical arsenal.

Syria was not required to declare its stockpile of chlorine -- a toxic but weak agent -- as it is widely used for commercial and domestic purposes.

But its use for military purposes would still be a breach of Damascus's undertakings under the convention.

Activists and doctors have also alleged the use of chlorine gas as a weapon targeting rebel-held areas in Idlib province, in northwestern Syria.