State (IS) group 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
No civilians were affected by the explosion, the ministry said.
The US military said the bomb was used purely on tactical grounds, "the right weapon against the
A statement on the IS-supporting Amaq news agency denied there were any IS casualties in the
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
Gen Nicholson said 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."
Achin district governor Ismail Shinwary told the BBC that Afghan special forces, with the help of
American air support, had begun anti-IS operations in the area 13 days ago.
He said IS targets had been bombed regularly but "last night's bombarding was very powerful… the
biggest I have ever seen".
Nangarhar Provincial Governor Gulab Mangal said IS fighters had used the complex to "kill people
and hold important meetings".
Massive blast area – Jonathan Marcus, BBC defence correspondent
The clue is in the ungainly name – the MOAB or GBU-43/B massive ordnance air blast is the US
military's most destructive conventional (that is non-nuclear) bomb.
It is a huge weapon and is GPS-guided. It was dropped from a MC-130 aircraft – the US Special Forces
variant of the Hercules transport. The weapon is carried on a special cradle inside the aircraft from
which it is extracted by a parachute.
Its principal effect is a massive blast over a huge area. It is a larger version of weapons used during
the Vietnam War.