Twenty-two pro-Ankara Syrian rebels were hit by a chemical gas attack from Islamic State (IS) militants in northern Syria, the Turkish army said on Sunday.
"After a rocket was fired by Daesh (IS), 22 opposition members were observed to have been exposed in their eyes and bodies to chemical gas," the general staff said in a statement, quoted by the state-run Anadolu news agency.
It said the attack happened in the area of the village of Khaliliya, east of Al Rai in northern Syria.
Turkish media said that the affected Syrian fighters were brought over the frontier to the Turkish border town of Kilis by teams from Turkey's AFAD emergencies agency.
The reports said that the Turkish emergency workers were equipped with special chemical suits to protect themselves. The Syrians were brought to the main hospital in Kilis where they are currently undergoing treatment.
Television pictures showed some of the Syrians being transferred on stretchers to the hospital, with the emergency workers dressed in full-body white protective clothing and gas masks.
The Turkish army is backing the Syrian fighters in an unprecedented incursion aimed at rooting out IS militants from the border area and also ensuring there is no Kurdish militia presence.
In a three-month operation, the rebels have so far captured the IS stronghold of Jarabulus, cleared IS from Al Rai and retaken the symbolically important town of Dabiq without much resistance.
With Turkish support, they are now pressing to take Al Bab from the militants in an advance that appears to be taking more time and encountering greater opposition.