Among those being considered are his spokesman Hakimullah, Azmatullah and Wali Ur Rehman.

Pakistan Interior Minister Rehman Malik said initial reports said Mehsud has been killed with his wife, a brother-in-law and seven bodyguards.

The missile strike, believed to have been carried out by a US unmanned 'drone' aircraft, struck the house of one of Mehsud's two fathers-in-law in South Waziristan, a tribal region near the Afghan border and a known hub of Al Qaeda and Taliban militants.

The strike came as Pakistani security forces were gearing up for a major offensive against Mehsud, who is blamed for dozens of terrorist attacks across the country and had been declared Pakistan's enemy number one.