KABUL, May 23 (Xinhua) -- At least four militants of the Islamic State (IS) outfit were killed after the Afghan air force launched airstrikes in eastern province of Nangarhar, the country's Defense Ministry said on Wednesday.

"The strikes were conducted in Achin district, Nangarhar province, on Tuesday and among the killed were one IS female fighter," the ministry said in a statement.

The mountainous province, 120 km east of Kabul, has been the scene of clashes between security forces and IS militants from time to time.

Clashes have forced thousands of villagers to flee to safer places.

The IS group, which emerged in Nangarhar in early 2015, has yet to make comments on the report.