But Baitullah Mehsud, the aide said, was ill and would take no action that would make it easier to hunt him down.
The comments by Hakimullah Mehsud compounded confusion that has surrounded Mehsud's reported death in a U.S. missile attack last week.
"Both I and our amir (leader) Baitullah Mehsud are alive," Hakimullah Mehsud told Reuters by telephone from an undisclosed location.
Pakistani and U.S. officials say they are quite certain that Baitullah, an al Qaeda cohort, was killed in the missile strike delivered by a drone on his father-in-law's house in the South Waziristan tribal region last Wednesday.
Baitullah's second wife, whom he married late last year, perished in the attack.
Pakistani Interior Minister Rehman Malik said on Saturday that Hakimullah had been involved in a shootout with a rival for the Taliban leadership, Wali-ur-Rehman, and that one of them was reportedly killed. Pakistani intelligence officials and media reported that Hakimullah was most probably dead.
Wali-ur-Rehman, speaking by telephone from an undisclosed location to Reuters on Sunday, also denied that any tribal council meeting, or shura, had taken place to decide on a successor to Baitullah.
Aide Challenges Government
Hakimullah said there had been no shura as Baitullah was alive.
"I have proven the government's claim of my death wrong and I challenge the government to prove the death of our amir. Baitullah Mehsud is alive, safe and sound," he said.
The Taliban, he said, would produce evidence within days to prove Baitullah was alive. "Let the interior minister prove he is dead. If the interior minister fails to prove Baitullah Mehsud's death, then I will produce evidence that he is alive."
Hakimullah echoed comments by another Taliban official that Baitullah, who suffers from diabetes, was ill.
"Drones are still flying in the area. The government is provoking Baitullah to speak on the telephone so that he can be targetted and killed, but he will not do so," he said.
But Interior Minister Malik insisted on Monday that Baitullah was dead.
"We may not have material evidence for now, but we have credible information from intelligence agencies that he has perished," he told the National Assembly, parliament's lower house.
Independent verification of the claims and counter-claims is extremely difficult as the Mehsud lands where the U.S. missile struck the house of Baitullah's father-in-law are remote and inaccessible.
