A spokesman for the Taleban in Pakistan has denied media reports that leading militant Baitullah Mehsud has died of an illness.
The spokesman, Maulvi Umar, told the BBC that Mr Mehsud was "fit and well".
Television channels reported that Mr Mehsud, who leads an alliance of pro-Taleban groups, died on Tuesday night.
Mr Mehsud is accused of masterminding the killing of former Pakistani Prime Minister Benazir Bhutto. He denied involvement in the attack.
Rumours of the militant's death have also been denied by his doctor, Eisa Khan.
"I spoke to him today at 9am on the telephone, and he told me that he is surprised over rumours about his death," Mr Khan told the Associated Press news agency.
Several other Pakistani Taleban spokesmen also insisted Mr Mehsud is healthy, with some even saying that he is due to marry his second wife this weekend.
Unnamed Pakistani officials had said that Mr Mehsud, head of the Tehreek-e-Taleban Pakistan (TTP), is seriously ill with diabetes and may even be in a coma.
"Baitullah is sick. His condition is precarious," a senior Pakistani security official told the AFP news agency on condition of anonymity.
Mr Mehsud - an ethnic Pashtun tribesman in his mid-30s - was recently named in Time magazine's 100 most influential people in the world. Newsweek has called him "more dangerous than Osama Bin Laden".
Rumours about his poor health have grown in recent weeks with Pakistani newspapers and television reporting him suffering from typhoid in addition to diabetes.
Mr Mehsud's commanders have admitted he is not well and the BBC's Barbara Plett in Islamabad says he has gone into a diabetic coma on at least one occasion.
Our correspondent says that if the militant leader were to be incapacitated or to die - questions would arise about the future of the Pakistani Taleban.
Mr Mehsud does not like to be seen in public
His commanders suggest that reports of his death are government propaganda.
The Tehreek-e-Taleban Pakistan is a network of Pashtun tribesmen linked to the Afghan Taleban - as well as the more radical jihadist groups linked to al-Qaeda - which have been blamed for a lot of the recent violence in Pakistan.
Mr Mehsud, who belongs to the Mehsud tribe in South Waziristan, openly advocates using suicide bombers and is blamed for dozens of such attacks in Pakistan over the past year.
He is said to have played a major role in providing a sanctuary for fighters to operate in Afghanistan.
Speaking to the BBC in 2007, he said the militants were determined to free Afghanistan through jihad (holy war).
"Only jihad can bring peace to the world," he said.
The militant leader on several occasions has openly admitted to crossing the border to fight foreign troops.
Since 9/11 he has grown in strength and stature, making him the most important pro-Taleban militant commander in the Waziristan region.