Many Afghans have expressed shock or doubt that the head of al-Qaeda was killed in Kabul by a US drone strike, saying they cannot believe that Ayman al-Zawahiri was hiding among them.

It's just propaganda, Fahim Shah, 66, a resident of the Afghan capital, told AFP.

U.S. President Joe Biden announced the killing of Zawahiri, saying justice has been served.

A senior US official said Zawahiri, 71, was on the balcony of a three-story house in the upmarket Sherpur neighborhood when two Hellfire missiles fired at him shortly after dawn.

Earlier Tuesday, the Taliban acknowledged that the US carried out the drone strike, but did not provide details of casualties or name Zawahiri, who was seen as a key conspirator of the 9/11 attacks on the United States.

On Sunday, the interior ministry denied reports of a drone strike, but on Tuesday, Taliban spokesman Zabihullah Mujahid said there was one.

Kabul resident Abdul Kabir said he heard the explosion on Sunday morning but still urged the United States to prove who was killed.

The strike will no doubt further sour an already tense relationship between Washington and the Taliban, who have pledged to keep Afghanistan from becoming a safe haven for militants as part of an agreement that led to the withdrawal of US troops last year.

University student Mohammad Bilal was another who thought it unlikely that Zawahiri lived in Kabul.