Isis has claimed that the so-called "mother of all bombs" dropped by US forces on a mountain hideout in Afghanistan did not kill any militants.
Afghanistan officials said that the bombing killed at least 36 Isis militants but caused no civilian casualties at a remote mountain hideout in eastern Afghanistan near the Pakistan border.
Some sources suggested that up to 82 militants had died in the blast.
The GBU-43/B Massive Ordnance Air Blast bomb, the largest ever non-nuclear bomb to be used in warfare, was dropped on Thursday (13 April) in Nangarhar province. Senior US officials also claimed that no civilian deaths were reported.
But the Isis propaganda agency Amaq went further and said that no militants were killed.
"Security source to Amaq agency denies any dead or wounded from yesterday's American strike in Nangarhar using a GBU-43/B."
The US army used the 9,800kg bomb, which weighs almost as much as a double-decker bus, to target a tunnel complex used by the insurgents who are battling both the Afghan army and the Taliban in Afghanistan.
Former Afghan president Hamid Karzi condemned the attack, calling it was "brutal and inhuman". He accused the US of using Afghanistan as a testing ground for new ordnance.
US General John Nicholson, Nato commander in Afghanistan, said: "This is the right weapon for the right target".
The bombing followed heavy fighting in recent weeks between the Afghan army and Isis extremists in Nangarhar province.
Gen Daulat Waziri, of the Afghanistan Ministry of Defence, said the bombing was necessary because the tunnel complex was difficult to penetrate.
"It was a strong position. Four times we had operations [attacking the site] and it was not possible to advance," he said. The road leading to the complex was full of mines, he explained.
In the Afghan village of Achin, just a few miles from where the bomb struck, resident Palstar Khan said, according to Sky News: "Last night's bomb was really huge. When it dropped, everywhere was shaking."