"This is work of the enemies of Afghanistan," he said, using a term that refers to the Taliban movement.
There was no immediate claim of responsibility from the Taliban.
The attack was the deadliest on Afghan soldiers in months, but about 20 security officials have been killed in blasts over the past two weeks.
The suicide attacker detonated his explosives close to the vehicle of a district governor of Paktika, which is on the border with Pakistan.
The bomber was the only individual to die in the attack.
Southern and southeastern Afghanistan have witnessed the majority of attacks by Taliban fighters. The Taliban was forced from government in late 2001.
Taliban fighters use roadside bombs and have launched suicide bombings at Afghan security forces and thousands of foreign troops in the country assisting them.
Despite a crackdown by Nato forces in Afghanistan's Helmand province, Taliban fighters maintain a strong presence in the region.
|Taliban fighters possess significant amounts|
of explosive for anti-tank bombs
Nato's Operation Achilles is into its seventh week but is meeting fierce resistance from the Islamist fighters.
A team featuring James Bays, Al Jazeera's Afghanistan correspondent, met some Taliban fighters in Helmand province standing on top of a burnt-out Nato military vehicle.
A cameraman attached to Bays' team was taken to a separate area where the Taliban showed him a store-room of explosives, which were in the process of being manufactured into anti-tank bombs.
The Taliban fighters also said they possess anti-aircraft weaponry, although they did not permit Al Jazeera to film such equipment.
"Thanks to God we have good guns ... we are ready all the time to face them [Nato and Afghan government forces] in a battle," one Taliban fighter said.