The US military confirmed Friday it had killed Al-Qaeda's emir for northeastern Afghanistan during an air strike last month, in a major blow to the group as it seeks to re-establish safe havens in the country.

Pentagon spokesman Peter Cook described the assault that killed Farouq al-Qahtani as a "precision strike" and said it took place on October 23 in Kunar, Afghanistan.

"This successful strike is another example of US operations to degrade international terrorist networks and target terrorist leaders who seek to attack the US homeland, our interests and our allies abroad," Cook said in a statement.

He said another Al-Qaeda leader in the country, Bilal al-Utabi, was targeted in a separate strike, though the results of that attack were not yet known.

Last month, US official said multiple Hellfire missiles had leveled two compounds in Kunar where the men were believed to be hiding.

One US official said the attack represented the most significant strike against the Al-Qaeda leadership in Afghanistan in years.

The Pentagon has been actively hunting for Qahtani for four years. He had longstanding ties with Osama bin Laden before his death in the 2011 US raid on his Pakistan compound.

Qahtani has operated in Afghanistan since at least 2009 and led an Al-Qaeda battalion since at least mid-2010.

His deputy Utabi was seen as the second- or third-most senior Al-Qaeda leader in Afghanistan.

US forces say airstrikes 'very likely' caused Afghan casualties
Kabul (AFP) Nov 5, 2016 - US forces conceded Saturday that its air strikes "very likely" resulted in civilian casualties in Afghanistan's volatile Kunduz province, pledging a full investigation into the incident which triggered angry protests.

The strikes early Thursday killed at least 30 people, many of them children, after a Taliban assault left two American soldiers and three Afghan special forces soldiers dead in the Boz-e-Kandahari area near the provincial capital.

"The president of Afghanistan has sent a special delegation to Kunduz to investigate the incident. Any negligence by anyone will be punished," presidential spokesman Haroon Chakhansuri told reporters.

US military spokesman Charles Cleveland said an initial probe showed the attack "very likely resulted in civilian casualties".

The carnage triggered impassioned protests in Kunduz city, with the victims' relatives parading mutilated bodies of dead children piled into open trucks through the streets.

"Look around me -- everyone is in deep pain," Sultan Mohammad said, carrying the body of a victim for the mass funeral ceremony on Friday.

"What was their crime? Why were they killed like this?"

He joined a growing chorus of people calling to bring the perpetrators to justice.

The carnage underscores worsening insecurity after the Taliban last month overran the city for the second time in a year, as NATO-backed Afghan forces struggle to rein in the insurgents.

US-backed Afghan special operations forces were conducting an operation against the Taliban on the outskirts of Kunduz city when they came under insurgent fire, prompting calls for air support.

"I deeply regret the loss of innocent lives, regardless of the circumstances. The loss of innocent life is a tragedy and our thoughts are with the families," said John Nicholson, the top US and NATO commander in Afghanistan.

"We will work with our Afghan partners to investigate and determine the facts."

The strikes also killed some top Taliban commanders, defence ministry spokesman Daulat Waziri said.

"Some civilians killed were members of their families," he added.

Civilian casualties caused by NATO forces have been one of the most contentious issues in the 15-year campaign against the insurgents, prompting strong public and government criticism.

Errant air strikes contributed to a 42 percent jump this year in casualties caused by pro-government forces compared to last year, according to the UN.