Turkey's health minister Recep Akdağ said that on Tuesday, tests on victims of a suspected chemical attack in Syria's northwestern Idlib province confirmed the use of sarin gas.
Both Washington and Ankara blame the Syrian government for the poison gas attack which killed nearly 100 people including children, but Damascus has denied responsibility.
The United States launched missile strikes last week against a Syrian government air base in response.
Akdağ was quoted as saying that isopropyl methylphosphonic acid "has been identified in the blood and urine tests conducted on samples taken from the victims exposed to chemical warfare in Idlib". The acid is formed from the degraded byproduct of sarin reacting with other compounds.