By Josh Smith
KABUL (Reuters) - Afghan forces backed by U.S. air strikes 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.
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," said Col. Michael Lawhorn. "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.
Militants claiming allegiance to Islamic State have taken advantage of the war between the government and insurgent groups like the Taliban to seize territory.
That prompted American leaders in December to relax restrictions on air strikes and allow U.S. warplanes to attack targets linked to Islamic State.
Since then, U.S. air strikes have spiked, with American warplanes using their weapons 128 times in January, more than three times as often as January 2015. In late January and early February, at least 20 air strikes hit Islamic State targets, military officials said.
"The air strikes are very useful and we have been able to make progress with their help," said Sherin Aqa, spokesman for the Afghan army's 201st Corps. "The air strikes must continue for us to stop Daesh."
The Afghan troops coordinated intelligence with U.S. forces who conducted the attacks, he added.
While Islamic State has not had the same success in Afghanistan as it has in Iraq and Syria, the group's fighters have proven well-equipped, motivated, and willing to use brutal tactics on civilians and security forces alike, military officials say.
(Additional reporting by Rafiq Sherzad; Editing by Nick Macfie)