JALALABAD: Afghan aircraft killed more than 40 fighters loyal to Islamic State in a raid in the eastern province of Nangarhar, officials said on Friday.

Although casualty claims by all sides are difficult to verify, Thursday's operation appears to have been an unusually large strike by Afghanistan's fledgling air force, which has been building up its capacity since the withdrawal of the Nato-led coalition from most combat operations in 2014.

“Based on our intelligence, the Afghan air force carried out the strike and killed more than 40 Daesh fighters,” Khogyani told Reuters, using a common Arabic acronym for Islamic State.

He said the militants had gathered to launch attacks in Nangarhar, bordering lawless areas of Pakistan.

The Afghan army public relations directorate said 42 IS militants had been killed in a joint operation in Nangarhar and a training centre destroyed. It said the Afghan air force had carried out 83 fighting operations around the country, causing heavy casualties to both the Taliban and IS.

Forces inside Afghanistan allied to Islamic State, whose core territory covers swathes of Syria and Iraq, have stepped up attacks against the much larger Afghan Taliban movement in pockets of the country's east.

In the past few months, the US fighter planes have also struck against Islamic State fighters in Nangarhar, forcing dozens to relocate to the rugged mountain terrain of the neighbouring province of Kunar.

A US military spokesman said the United States has carried out 70 to 80 air strikes against Islamic State in Afghanistan in the three months since the US forces were given broader authority to target militants in January.

Although Afghan forces still depend heavily on US air power for both logistics and close combat support, the local air force has been building up its strength as more pilots and air crew qualify and more aircraft are delivered.

As part of its buildup, the air force took delivery of a first batch of A-29 Super Tucano attack aircraft in February.

The A-29 took part in their first independent operation in the northern province of Badakhshan on Thursday, and the Afghan air force was steadily improving targeting and approvals to minimize civilian casualties, the new commander of the Nato-led coalition in Afghanistan, US General John Nicholson said.

“It's much more than just the pilot being able to fly the plane and release the ordnance, there's a whole system that surrounds this,” he told Reuters in an interview this week.