Afghan forces backed by U.S. airstrikes have killed dozens of insurgents loyal to Islamic State this week as they continue a push into areas occupied by the radical group, officials said on Tuesday, February 23, Reuters reports.

For months, security forces have been trying to dislodge Islamic State fighters from Achin district, an area in eastern Nangarhar province along the border with Pakistan.

More than 30 militants were reported killed in the most recent fighting, said Attaullah Khogyani, a spokesman for the Nangarhar provincial government.

"Daesh fighters who had gathered in Mohman Dara village were attacked by a drone," he said, using an Arabic acronym for Islamic State.

Khogyani said as many as 22 were killed in the air strike on Monday, but a U.S. military spokesman would not publicly confirm casualty numbers.

"U.S. forces conducted a counter-terrorism strike in the Achin district, Nangarhar province, yesterday," Reuters cited Col. Michael Lawhorn as saying. "For reasons of operational security, we do not discuss counter-terror operations."

Another 15 insurgents died in a gun battle with Afghan troops, Khogyani said, but that number could not be verified.