Pakistan security officials believe Baitullah Mehsud, commander of the Pakistani Taliban, has been killed by a US missile.
US and Pakistani officials accuse the Taliban chief of masterminding the 2007 assassination of ex-Pakistani prime minister Benazir Bhutto and blame him for the deaths of hundreds of people in bomb attacks over the past two years.
Senior officials in Pakistan's powerful security establishment who supervise operations in Mehsud's Waziristan stronghold said the warlord was dead.
Foreign Minister Shah Mahmood Qureshi told reporters intelligence reports indicated the Taliban leader was dead but he was awaiting verification.
Taliban leaders have gathered in South Waziristan to choose a successor, local sources have told the BBC.
Three names are under consideration and it is possible the Taliban are waiting to choose their new leader before announcing Baitullah Mehsud's death, says Abdul Hai Kakar, a BBC reporter based in Peshawar.
US officials say the death of Baitullah Mehsud, if confirmed, was unlikely to cripple the Taliban in Pakistan, as he has thousands of people in his network.
Tribesmen said that the Taliban leader and his wife were killed when a US drone fired two missiles into a family home in the Laddah area of South Waziristan on Wednesday.
The US Central Intelligence Agency, with the tacit cooperation of Islamabad, has carried out dozens of attacks in Pakistan using unmanned Predator and Reaper drones over the past year, but declines to discuss the strikes publicly.