Less than 48 hours after the United States launched the ‘Mother Of All Bombs’ on an Islamic State stronghold in Afghanistan, its top military commander has defended the decision as “purely tactical” and not based on “broader political considerations”.

NATO commander in Afghanistan, US General John W Nicholson, said “it was the right time to use it tactically against the right target on the battlefield”.

Afghan and US forces were at the scene of the strike and reported that the “weapon achieved its intended purpose”, General Nicholson said.

Ataullah Khogyani, spokesman for the provincial governor in Nangarhar, said the number of militants killed in an attack by the largest non-nuclear weapon ever used in combat by the US military has risen to 96, up from the 36 reported a day earlier.

There were no civilian casualties, officials said.

The statement could not be independently verified, and on Friday Afghan and foreign troops in the vicinity were not allowing reporters or locals to approach the scene of the attack.

The Islamic State group has denied suffering any casualties, issuing a statement through its propaganda agency Amaq, saying: “Security source to Amaq agency denies any dead or wounded from yesterday’s American strike in Nangarhar using a GBU-43/B.”

Pentagon officials said the US commander who ordered the use of the bomb did not need President Donald Trump’s approval.

General Nicholson has had standing authority since before Mr Trump took office to use the largest non-nuclear bomb ever dropped in combat.

He said he was in constant communication with officials in Washington, but the decision to use the 9,797-kilogram GBU-43 bomb was based on his assessment of military needs and not broader political considerations.

“This was the first time that we encountered an extensive obstacle to our progress,” General Nicholson said of a joint Afghan-US operation that has been targeting IS fighters since March.

Afghan Defence Ministry spokesman Dawlat Waziri said no civilians were harmed in the massive blast that targeted the network of caves and tunnels, which had been heavily mined.

“No civilian has been hurt and only the base, which Daesh [IS] used to launch attacks in other parts of the province, was destroyed,” General Waziri said in a statement.

Afghan forces were at the tunnel complex assessing the damage, he added.

General Waziri said the bombing was necessary because the complex was extremely hard to penetrate, with some tunnels as deep as 40 metres.

“It was a strong position and four times we had operations [attacking the site] and it was not possible to advance,” he said, adding that the road leading to the complex “was full of mines”.

General Nicholson said the decision to use the 9,797-kilogram GBU-43 bomb was based on his assessment of military needs and not broader political considerations.

The GBU-43 is a GPS-guided munition that had never before been used in combat since its first test in 2003, when it produced a mushroom cloud visible from 32 kilometres away.

The bomb’s destructive power, equivalent to 11 tonnes of TNT, pales in comparison with the relatively small atomic bombs dropped on Japan at the end of World War II, which had blasts equivalent to between 15,000 and 20,000 tonnes of TNT.

Meanwhile, former Afghanistan president Hamid Karzai was among the first to condemn the bombing.

I vehemently and in strongest words condemn the dropping of the latest weapon, the largest non-nuclear #bomb, on Afghanistan by US…1/2

— Hamid Karzai (@KarzaiH) April 13, 2017

2/2 military. This is not the war on terror but the inhuman and most brutal misuse of our country as testing ground for new and dangerous…

— Hamid Karzai (@KarzaiH) April 13, 2017

2/3 weapons. It is upon us,Afghans, to stop the #USA.

— Hamid Karzai (@KarzaiH) April 13, 2017

— with ABC/AAP