Islamabad (Agencies): In another brutal incident related to the Pakistani Taliban, a former officer of the country's intelligence agency, the Inter-Services Intelligence (ISI), was shot to death after he was kidnapped from the northern tribal region.

A Taliban militant is shown in the video firing at former ISI officer, Col (Retd) Sultan Ameer Tarar, also known as Colonel Imam, in the presence of Pakistani Taliban chief Hakimullah Mehsud.

Col Imam was killed on January 23 by the Pakistani Taliban in North Waziristan.

Imam and former ISI official Squadron Leader (Retd) Khalid Khawaja had gone to North Waziristan along with BBC journalist Asad Qureshi and his driver Rustam Khan to film documentary on the Pakistani Taliban and victims of US drone strikes, when they were kidnapped in March 2010.

Later, an unknown militant organisation, Asian Tigers, claimed responsibility for the kidnapping and accused Khalid Khawaja of spying for the CIA. He was then shot dead on April 30 near Mir Ali town. Col Imam was kept alive and held hostage all through until his execution on January 23.

Pakistan Human Rights Commission chief IA Rehman condemned the killing and remarked it as a brutal act.

The Taliban had previously released a video of Khawaja in which he was heard admitting his links with the ISI and CIA and playing a double game with the Taliban.

Taliban sought Rs 50 million for setting free Imam but negotiations in this regard made no headway and he was killed.

Imam had served 11 years in the ISI out of 18 years in the armed forces, while Khwaja served for 22 years in the air force.