The attack occurred near al-Bab, a town about 25 miles (40 kilometres) east of Aleppo under control of pro-Turkish forces, Turkish Red Crescent President Kerem Kinik said in a tweet, without identifying the perpetrators.

"One of our colleagues from the Red Crescent was martyred and another was injured in the attack," said Kinik, adding that a third staff member was unharmed.

The Turkish Red Crescent said its vehicle was clearly displaying the organisation's symbol when it was attacked by an unknown number of masked gunmen who wore camouflage clothing.

It added in a statement the wounded person did not suffer life-threatening injuries, and would be taken to Turkey after initial medical treatment.

The Turkish defence ministry also condemned the attack in a statement, vowing "every measure is being taken on land and by air to catch the terrorists who attacked an aid organisation which is untouchable under international law."

But the ministry did not blame any specific group for the killing.

Turkey controls large stretches of northeastern Syria through various armed groups, and is conducting operations aimed at driving out Kurdish militias and jihadists.

The Turkish army recaptured al-Bab from the Islamic State group in 2017 during Ankara's first cross-border offensive.