Health Minister Recep Akdağ confirmed on Tuesday that sarin gas was definitely used in the attack carried out in Syria's Idlib province last week.

"The use of sarin gas in Idlib, has become certain," Akdağ said, following testing on blood and urine samples of victims of the attack in Khan Sheikhoun.

The results showed traces of sopropyl methyl phosphonic acid, the metabolite of sarin, a banned nerve agent.

More than two dozen victims of the attack were brought to Turkey for treatment and three died in a Turkish hospital. Ground samples were also brought across the border from Idlib for testing.Officials from the World Health Organization and the Organization for the Prohibition of Chemical Weapons participated in the autopsies.

Autopsy results were sent last week to The Hague for further testing by the United Nations.