At least five security personnel were killed and 10 injured when a suicide bomber blew himself up near an army vehicle outside a Pakistan army camp in the troubled South Waziristan region on Thursday.

The suicide attacker detonated his explosives just as the vehicle was leaving the army camp in Wana, the headquarters of South Waziristan, at 2.30 pm, Dawn News channel quoted official sources as saying.

Some reports said that seven personnel were killed in the attack. Initial reports had suggested that militants had attacked the army camp with rockets.

Eyewitnesses said columns of smoke were seen rising from near the camp.

Observers said the attack could have been carried out by pro-Taliban militants in retaliation for a missile strike on a residential compound in South Waziristan four days ago that killed 20 people and injured 10 others.

Local residents had said that the attack could have been carried out by United States-led forces in Afghanistan, who had launched at least two missile strikes on Pakistan's northwestern tribal areas with pilotless drones last month,  including an attack that killed top Al Qaeda [Images] commander Abu Laith al Libi on February 4.