One of the most senior al-Qaeda militants in Pakistan, Badar Mansoor, has been killed in a US drone strike, local officials say.
The attack took place in Miranshah in North Waziristan tribal area, close to the border with Afghanistan.
Badar Mansoor is suspected of killing dozens of people in attacks in Pakistan and further afield.
If confirmed, his death would be seen by the US as a vindication of its drone programme, correspondents say.
Al-Qaeda has so far not publicly commented on the claim, but AFP news agency has quoted one Mansoor loyalist confirming the death.
Pakistani officials say he was among at least four militants killed in the pre-dawn strike.
Badar Mansoor had moved between the militant groups of Harkat-ul-Mujahideen, the Pakistani Taleban and al-Qaeda where he became a key figure, the BBC's Aleem Maqbool in Islamabad says.
He is thought to have trained new fighters and planned numerous suicide attacks, including one against Pakistan's Ahmadi Muslim minority in Lahore in which about 90 people died, our correspondent adds.
The drone attack was the second in North Waziristan in as many days. On Wednesday, 10 suspected militants were killed, Pakistani security officials said.
Drone attacks cause huge anger in Pakistan, which has previously complained that they violate its sovereignty. However, correspondents say the authorities are believed privately to give their support to the US for the attacks.
Last month, US President Barack Obama defended the use of drones to target militants in Pakistan's tribal areas.
The US does not normally comment on drone operations, which have killed hundreds of people in recent years. The dead include senior al-Qaeda and Taliban leaders, as well as an unknown number of other militants and civilians.