In a scene that recalled the kind of pre-9/11 reign of terror that many thought ended with the U.S. invasion of Afghanistan, a video showing the public execution of a woman accused of adultery by a Taliban militant has sparked outrage in the country and around the world.

The three-minute video, obtained by Reuters, shows a woman in a burka being shot repeatedly as some 150 men cheer and yell "mujahideen." The killing took place in Charikar in Parwan Province, not far from the capital of Kabul.

"After 10 years (of foreign intervention), and only a few kilometres from Kabul... how could this happen in front of all these people?" said Fawzia Koofi a female lawmaker and campaigner for girls' education after watching the video. "It is really very much a sharp turn, and a huge backward (step)."

The Taliban have denied involvement in the execution but the religious extremist group has a long history of meting out harsh punishment to those deemed sinners.

U.S. General John Allen, NATO's top commander in Afghanistan, called the latest killing "an atrocity of unspeakable cruelty" as the hunt for the killer began and locals vowed retaliation.

"We will take revenge for this," said Sayed Jalal, a local shopkeeper in the town where the woman was killed. "Their brutality and such inhumane acts are why we hate the Taliban."