(Reuters) – US President Joe Biden in a live address said: "Justice has been delivered" in US strike killing al-Qaida leader al-Zawahri; "this terrorist leader is no more." He confirmed reports that began hours earlier about the attack.

Al Qaeda leader Ayman al-Zawahiri was killed in a US drone strike in Afghanistan over the weekend, Biden confirmed and US officials said earlier, the biggest blow to the militant group since its founder Osama bin Laden was killed in 2011.

Zawahiri, an Egyptian surgeon who had a $25 million bounty on his head, helped coordinate the Sept. 11, 2001, attacks that killed nearly 3,000 people.

One of the US officials, speaking on the condition of anonymity, said the CIA carried out a drone strike in the Afghan capital Kabul on Sunday.

"Over the weekend, the United States conducted a counterterrorism operation against a significant al Qaeda target in Afghanistan," a senior administration official said.

"The operation was successful and there were no civilian casualties," the official added.

It was not immediately clear how the United States, which does not have US troops on the ground, confirmed that Zawahiri had been killed.

There were rumors of Zawahiri's death several times in recent years, and he was long reported to have been in poor health.

His death raises questions about whether Zawahiri received sanctuary from the Islamic Emirate following their takeover of Kabul in August 2021.

The drone attack is the first known US strike inside Afghanistan since US troops and diplomats left the country in August 2021. The move may bolster the credibility of Washington's assurances that the United States can still address threats from Afghanistan without a military presence in the country.

In a statement, Islamic Emirate spokesman Zabihullah Mujahid confirmed that a strike took place and strongly condemned it, calling it a violation of "international principles."

A loud explosion echoed through Kabul early Sunday morning.

"A house was hit by a rocket in Sherpoor. There were no casualties as the house was empty," Abdul Nafi Takor, spokesman of the interior ministry, said earlier.

One Taliban source, requesting anonymity, said there had been reports of at least one drone flying over Kabul that morning.

With other senior al Qaeda members, Zawahiri is believed to have plotted the October 12, 2000, attack on the USS Cole naval vessel in Yemen which killed 17 US sailors and injured more than 30 others, the Rewards for Justice website said.

He was indicted in the United States for his role in the August 7, 1998, bombings of the U.S. embassies in Kenya and Tanzania that killed 224 people and wounded more than 5,000 others.

Zawahiri's whereabouts – variously rumored to be in Pakistan's tribal area or inside Afghanistan – had been unknown until the strike.

A video released in April in which he praised an Indian Muslim woman for defying a ban on wearing an Islamic head scarf dispelled rumors that he had died.

Both bin laden and Zawahiri eluded capture when US-led forces toppled Afghanistan’s Islamic Emirate government in late 2001 following the Sept. 11 attacks on the United States.

Bin Laden was killed in 2011 by US forces in Pakistan.