A US military strike with a weapon known as the “mother of all bombs” (MOAB) killed 36 IS militants and destroyed their base, the Afghan defence ministry says.
The most powerful non-nuclear bomb ever used by the US in combat was dropped on IS tunnels in Nangarhar province.
No civilians were affected by the explosion, the ministry said.
Former Afghan President Hamid Karzai condemned the attack as “an inhuman and most brutal misuse of our country”.
Chief Executive of Afghanistan Abdullah Abdullah confirmed that the attack had been carried out in co-ordination with the government and that “great care had been taken to avoid civilian harm”.
In a press briefing on Friday, Gen John Nicholson, commander of US forces in Afghanistan, said: “We have US forces at the site and we see no evidence of civilian casualties nor have there been reports.”
The Afghan defence ministry said the bomb struck a village area in the Momand valley where IS fighters were using a 300m-long network of caves.
It said the 21,600lb (9,800kg) bomb also destroyed a large stash of weapons.
Presidential spokesman Shah Hussain Murtazawi told the BBC that IS commander Siddiq Yar was among those killed. Mr Murtazawi said the IS fighters in the tunnels had “come from Pakistan and were persecuting people in the local area”.
The GBU-43/B Massive Ordnance Air Blast Bomb was dropped by plane in Achin district on Thursday evening local time, the Pentagon said.
More than 9m (30 ft) in length, it was first tested in 2003 but had not been deployed in combat before.
Gen Nicholson said it was “the right weapon against the right target” and “it was the right time to use the GBU-43 tactically”.
He added: “Let me be clear – we will not relent in our mission to destroy [IS in Afghanistan]… There will be no sanctuary for terrorists in Afghanistan.”