The bomb, detonated remotely, hit the vehicle of official Farooq Wazir in Raghzai area of South Waziristan district, a senior security official told AFP.
Wazir and two others were killed on the spot, the official said. Local intelligence officials confirmed the blast and casualties.
Prime Minister Nawaz Sharif “strongly condemned” the blast and “deplored the loss of life and extended condolences to the bereaved families,” a government statement said.
Pakistan has been battling a homegrown Islamist insurgency for over a decade following the 2001 US-led invasion of Afghanistan.
The Pakistan army began a major campaign against Taliban and other militant strongholds in the neighbouring North Waziristan tribal area in June last year and authorities have now vowed to intensify operations in other border regions and across the country.
Elsewhere in South Waziristan Taliban militants killed two local tribesmen and dumped their bodies in a marketplace, accusing them of spying for the United States. -AFP