As many as 36 suspected Isis militants were killed in Afghanistan when the US dropped "the mother of all bombs," its largest non-nuclear device ever unleashed in combat, the Afghan Defence Ministry said on Friday.

The claims have not been independently verified, but ministry spokesman Dawlat Waziri said no civilians were harmed in Thursday's massive blast that targeted a network of caves and tunnels.

"No civilian has been hurt and only the base which Daesh used to launch attacks in other parts of the province, was destroyed," Waziri said in a statement, using an Arabic term for Isis, which has established a small stronghold in eastern Afghanistan and launched deadly attacks on the capital, Kabul.

The US Air Force dropped the so-called MOAB bomb on an area of eastern Afghanistan known to be populated by Isis-affiliated militants.

The Pentagon said the strike was the first time the 21,000lb weapon had been used in combat operations.

A spokesperson for the US Department of Defence confirmed to The Independent that an MC-130 cargo aircraft dropped a GBU-43 bomb at 7pm local time.

The weapon is known in the US Air Force by its nickname MOAB, or "mother of all bombs". MOAB stands for massive ordnance air blast.

Pentagon spokesman Adam Stump said the bomb was dropped on a cave complex believed to be used by fighters affiliated to Isis in the Achin district of Nangarhar, close to the border with Pakistan.

The mission had been in the planning stages for months, the Pentagon said in a separate statement. However, they "did not have the information" on whether the mission was being planned during the previous Obama administration.

US Army General John W Nicholson, commander of the country's forces in Afghanistan, said in a written statement that the strike was designed to minimise the risk to Afghan and US forces conducting clearing operations in the Achin area "while maximising the destruction" of Isis fighters and facilities. He said Isis has been using improvised explosive devices, bunkers and tunnels to strengthen its defences.

White House press secretary Sean Spicer said the US had used a “large, powerful and accurately-delivered weapon” to disrupt the movements of militants in the country.

But the former Afghan president Hamid Karzai condemned the use of the weapon on Afghan soil. "This is not the war on terror, but the inhuman and most brutal misuse of our country as testing ground for new and dangerous weapons," he posted on his Twitter account.

PJ Crowley, the assistant secretary of state in the Obama administration, compared the bomb – dropped on a complex of cave and tunnels – to “creating a minor earthquake” in the particular area.

“It’s going to have a profound effect not just in the immediate area but the concussion extends for a considerable distant,” he added on BBC's Radio 4 Today programme

“It is certainly something that will get the attention of military forces in that area. What impact it has – we’ll just have to wait and see.”

“We’re all fascinated by the weapon and it is a very large and stunning weapon but I think it’s the context that is more important. The Obama administration in its last four years was looking for an exit strategy for Afghanistan.”

But towards the end of his administration, the former official added, it became clear that it was not possible for the former President to vacate the region as it became clear the fragile Afghan government would collapse.

Old footage of 'Mother of All Bombs' test is thought to be same bomb as US' attack on Afghanistan

PJ Crowley added that using the bomb appeared to signal a shift in approach from the White House that the Trump administration is now willing to use a “more intensified” approach to military action in the region and “to regain some momentum in Afghanistan”.

According to Reuter’s news agency in a village around three miles from the blast site, homes and shops appeared unaffected by the bomb. Residents said they saw militants climbing up and down the mountain every day, making occasional visits to the village.

"They were Arabs, Pakistanis, Chinese and local insurgents coming to buy from shops in the bazaar," said resident Raz Mohammad.

On Friday, the village was swarming with Afghan and international troops, as helicopters and other aircraft flew overhead.

The strike was part of a joint operation between Afghan and international troops, Afghan President Ashraf Ghani's office said in a statement.