President Joe Biden expressed hope Monday that the killing of al-Qaida leader Ayman al-Zawahri brings "one more measure of closure" to families of the victims of the September 11, 2001, attacks on the United States.

Biden made the comments as he confirmed that a US drone strike in Afghanistan this weekend killed al-Qaida leader Ayman al-Zawahri.

"He will never again, never again, allow Afghanistan to become a terrorist safe haven because he is gone and we're going to make sure that nothing else happens," Biden said in an address from the White House formally announcing the operation.

"This terrorist leader is no more," Biden said.

Al-Zawahri, the top al-Qaida leader, was killed by the US over the weekend in Afghanistan. Photo / AP

He said US intelligence officials tracked al-Zawahri to a home in downtown Kabul where he was hiding out with his family. The president approved the operation last week and it was carried out on Sunday.

The house Al-Zawahri was in when he was killed was owned by a top aide to senior Taliban leader Sirajuddin Haqqani, according to a senior intelligence official. The official also added that a CIA ground team and aerial reconnaissance conducted after the drone strike confirmed al-Zawahri's death. Planning for the operation began six months ago, but intensified in the last two months, the official said.

Over the 20-year war in Afghanistan, the US targeted and splintered al-Qaida, sending leaders into hiding. But America's exit from Afghanistan last September allowed the extremist group to rebuild. US military officials, including General Mark Milley, chairman of the Joint Chiefs of Staff, have said that al-Qaida was trying to reconstitute in Afghanistan, where it faced limited threats from the now-ruling Taliban.

Military leaders have warned that the group still aspired to attack the US.

- AP