Azam Tariq Mehsud, the spokesman for the Tehrik-e-Taliban Pakistan, says the group's deputy chief, Khalid Mehsud, also known as Commander Sajna, was killed in last Thursday's strike in the border village of Gorwak in North Waziristan, once a stronghold of militants.
He said another commander, Mufti Noor Wali, has now been appointed as the group's deputy chief.
Tariq says Wali enjoys the backing of Mullah Fazlullah, the leader of the Pakistani Taliban who is believed to be hiding in Afghanistan.
Islamabad opposes the drone strikes, saying they violate its sovereignty.