Pakistan's Taliban denied a report on Sunday that their leader Hakimullah Mehsud had been killed in a U.S. drone aircraft strike, Reuters reported.
Pakistan's military said earlier it was investigating the report that Hakimullah died from wounds sustained in a drone attack and had been buried in the Orakzai tribal region in the northwest of the country.
"We're inquiring further but so far there's no confirmation," said army spokesman Major General Athar Abbas.
Hakimullah's death would likely create disarray in Pakistan's al Qaeda-linked Taliban, analysts say, but it would not deal a major long-term blow to the group, which is fighting to topple the pro-American government.
State television did not give dates for the drone attack.
Pakistani intelligence officials said they had received unconfirmed reports that Hakimullah, the number one enemy of the Pakistani state, may have died of wounds after a drone strike on two vehicles carrying militants in North Waziristan on January 17, days after surviving a similar attack.
Hakimullah appeared in a farewell video with the suicide bomber double agent who killed seven CIA employees in Afghanistan on December 30.
The footage suggested his Tehrik-e-Taliban Pakistan (TTP), Taliban Movement of Pakistan, which has focused on fighting Pakistan's government, had become more sophisticated, taking part in the second deadliest attack in the CIA's history.
Pakistan's Taliban issued an audio tape on Jan 16. purportedly from Hakimullah denying he was killed in a U.S. drone strike two days earlier.
The intelligence officials said reports indicated Hakimullah was taken to Orakzai tribal region after the drone attack on the two vehicles, and that he may have been killed or wounded.
Washington sees Pakistan as a frontline state in its war against militancy and wants it to go after Afghan Taliban groups who cross the border and attack Western forces in Afghanistan.
But Pakistan says it does not have enough resources to open new fronts against militants and must concentrate on homegrown Taliban insurgents seeking to impose their austere form of Islamic rule in nuclear-armed Pakistan.
In August 2009, a U.S. drone strike killed Pakistan Taliban leader Baitullah Mehsud.
The Taliban have hit back with bombs that have killed hundreds since a security offensive launched in October that destroyed Hakimullah's bases in South Waziristan.
Hakimullah's deputy, Wali-ur-Rehman, is waiting in the wings if he is killed.
Pakistan militants warned of a full-blown war against the government if security forces launch any operation in the tribal region of North Waziristan, where Hakimullah is believed to have fled after the South Waziristan crackdown.
"We will not accept any sort of operation and if there is any preparation from the government for an operation, or government forces enter any village in this regard, that could trigger a full-fledged battle," said the Council of Mujahideen, which includes the Pakistani Taliban, in a statement.