The death toll from the American military's 11-ton and largest non-nuclear bomb ever used in combat almost tripled Saturday, with Afghan officials saying at least 90 ISIS jihadists were killed, as US-led forces conducted clean-up operations over the rugged terrain.

Afghan officials had earlier said the bombing had killed 36 IS fighters, adding that there there were "no military and civilian casualties at all".

On Friday, U.S. officials called the use of the GBU-43/B Massive Ordnance Air Blast bomb (MOAB) the right weapon at the right time.

A network of tunnels and caves was destroyed on Thursday evening local time, United States officials said.

The GPS-guided bomb is capable of destroying an area equivalent to nine city blocks.

The provincial government of Nangarhar province in the east of the country where this bomb was dropped, said on Saturday that the latest estimates suggest that the damage inflicted upon the militants is much more than initially believed.

'It was the right time to use it tactically against the right target on the battlefield'.

"This weapon was used against Isis-K and their sanctuary inside Afghanistan", NATO forces commander General John Nicholson said., according to the AP.

He said a clearance operation was continuing.

While US President Donald Trump lauded the strike, which killed almost 100 suspected militants as a "very, very successful mission", the response within Afghanistan has been mixed.

But former President Hamid Karzai accused the United States of using Afghanistan as "a testing ground for new and unsafe weapons".

Haji Mohammad Sadeq, another tribal elder said civilians in the immediate area of the Islamic State hideout "left the area long ago", while others who remained were alerted by Afghan forces through mosques.

Some in Pakistan said the explosion was so loud they thought a bomb had been dropped in their village.

This unprecedented use of power has stirred mix reaction in Afghanistan.

Afghan security force personnel take part in an ongoing operation against an Islamic State (IS) militant stronghold in Achin district of Nangarhar, eastern Afghanistan on April 14, 2017. The rocky landscape is dotted with caves and defensive tunnels, making it easy to hold and hard to attack, according to Nic Robertson, CNN's global diplomatic editor, who has reported from the Afghan mountains.