White House official: 'extremely unlikely' Turkey used chemical weapons against Kurds

The official acknowledged reports about an alleged toxic gas attack in Syria on Friday, reported AP.

Local doctors and Syria's state-run SANA news agency reported on Saturday that six civilians had trouble breathing after inhaling poison gas following a Turkish assault on Afrin.

Both SANA and the Syrian Observatory for Human Rights quoted local doctors in their reports.

The claims could not be independently verified, and videos released from the hospital showed people being fitted with oxygen masks who did not otherwise show symptoms of poison gas inhalation.

Ankara responded to the accusation with a statement on Saturday that it does not use "internationally-banned ammunition" in its Afrin campaign.

A Turkish diplomatic source also described the reports as "black propaganda," according to the Jerusalem Post.

Ankara launched an air and ground offensive against the Kurdish People's Protection Units (YPG) militia in northern Syria last month.

The White House's defence of Turkey comes a day after the NATO allies struck a deal to "work together" in Syria amid simmering tensions over US support for the YPG Kurdish militia that Turkey sees as an extension of the outlawed Kurdistan Workers Party (PKK).

US Secretary of State Rex Tillerson arrived in Turkey on Thursday for a two-day visit, engaging in "difficult negotiations" with President Recep Tayyip Erdogan that lasted more than three and a half hours.