GENEVA, Sept 6 (Reuters) – Syrian forces have used chemical weapons more than two dozen times during the country’s civil war, including in the deadly attack that led to U.S. air strikes on government planes, U.N. war crimes investigators said on Wednesday.

In the most conclusive findings to date from investigations into chemical weapons attacks during the conflict, the U.N. Commission of Inquiry on Syria said a government warplane dropped sarin on Khan Sheikhoun in Idlib province in April, killing more than 80 civilians.