Hakimullah Mehsud's predecessor was killed by a drone last year
There are fresh claims that the Pakistani Taliban chief Hakimullah Mehsud is dead, after state TV reported that he had been buried.
But within hours of the report the Taliban again denied Mehsud had been killed and challenged reporters to provide proof of it.
Pakistan's army said it could not confirm the death and said its agents were seeking clarification.
Reports of Mehsud's death first began after a drone strike on 14 January.
US drones have mounted numerous missile strikes in recent years, and killed the Taliban's former leader, Baitullah Mehsud, last August.
North and South Waziristan - where the Mehsud tribe comes from - are major sanctuaries for militants.
The army launched an offensive against the militants in South Waziristan in October and is under US pressure to do the same in North Waziristan.
'Alive and safe'
The state broadcaster reported the burial without giving any sources.
Born in South Waziristan, believed to be in his early 30s
Rose to prominence as mastermind of attacks on Nato convoys in Khyber region and Peshawara
Became Pakistani Taliban leader after predecessor's death in August 2009
Has reputation for daring and aggressiveness
A tribal elder told the Associated Press news agency on Sunday that he had attended Mehsud's funeral in the Mamuzai area of Orakzai on Thursday.
He was speaking on condition of anonymity for fear of retribution from the Taliban.
But the chief Taliban spokesman, Azam Tariq, dismissed the reports.
"Hakimullah is alive and safe," he told AFP news agency by telephone from an unknown location.
"The purpose of stories regarding his death is to create differences among Taliban ranks but such people will never succeed."
He stressed that the Taliban had released two audio tapes of Hakimullah Mehsud speaking since the 14 January attack on a compound in the Shaktoi area, in which 10 suspected militants died.
"People who are saying that Hakimullah has died should provide proof of it," the Taliban spokesman said.
Meanwhile, the Pakistani army's chief spokesman, Maj Gen Athar Abbas, said that his sources had no information either to confirm or deny Mehsud's death.
In another development, Reuters news agency quoted Pakistani intelligence officials as saying that Mehsud may have been targeted in a follow-up drone strike on 17 January.
The officials said they had received unconfirmed reports that he may have died of wounds sustained when a drone fired on two vehicles carrying militants in North Waziristan.
Hakimullah Mehsud recently appeared in a video alongside a Jordanian man alleged to have killed seven CIA agents in a suicide bombing in Afghanistan.
He has led the Pakistani Taliban since Baitullah Mehsud's death last summer.
It took the Taliban a number of weeks to admit that its previous leader had been hit in a missile strike.
Pakistan has publicly criticised drone attacks, saying they fuel support for the militants. But observers say in private the authorities have given the go-ahead for the strikes.
The US military does not routinely confirm such attacks, but analysts say the US armed forces and CIA in Afghanistan are the only forces capable of deploying drones in the region.