A manhunt was under way Monday for Taliban militants who publicly executed a woman accused of adultery, Afghan authorities said, as outrage mounted after a video of the cold-blooded killing surfaced.
President Hamid Karzai called the killing "disgusting and unforgivable" and ordered security forces to spare no effort in arresting and punishing those responsible.
The commander of NATO's 130,000 troops in Afghanistan, General John Allen, offered to help local security forces track and capture the men involved in what he called "an atrocity of unspeakable cruelty".
The brutal shooting of the lone woman before a cheering mob of men is shown in graphic detail in a video of the event in a village in Parwan province some 100 kilometres (60 miles) north of the capital Kabul.
"We have sent a police force to the area," Parwan provincial governor Basir Salangi told AFP, adding that the government had no permanent presence in the valley.
"They are searching for the Taliban who are responsible but the Taliban, including the killer, have fled to the mountains."
Roshna Khalid, Salangi's spokeswoman, separately told AFP the 22-year-old woman, named as Najiba, was married to a member of the hardline Islamist Taliban and was accused of adultery with a Taliban commander.
"Within one hour they decided that she was guilty and sentenced her to death. They shot her in front of villagers in her village, Qol," she said.
Public executions of alleged adulterers were common when the Taliban regime was in power from 1996 until 2001, when they were ousted by a US-led invasion for harbouring Al-Qaeda leader Osama bin Laden after the 9/11 attacks.
The Taliban have since waged an insurgency against the Western-backed government of President Hamid Karzai.
Karzai said Afghanistan's suffering people were not expecting a repeat of such incidents after the fall of the Taliban regime.
"Murdering a woman who did not even have a voice for defending herself is a sign of cowardness and such a crime is unforgivable in Islam and the country's laws," he said.
The video also drew international condemnation, with British Foreign Secretary William Hague saying he was "shocked and disgusted" by the execution.
"Such deplorable actions underline the vital need for better protection of the rights of women and girls in Afghanistan," he said.
US Secretary of State Hillary Clinton, before the video surfaced, made a powerful plea Sunday for the rights of women in Afghanistan, amid fears that recent gains for women are under threat as NATO troops prepare to leave in 2014.
Clinton, who was addressing a world conference in Tokyo on Afghanistan's future, said: "The United States believes strongly that no nation can achieve peace, stability and economic growth if half the population is not empowered."
The video opens with the woman, wrapped in a grey shawl, sitting at the edge of a ditch in a village surrounded by dozens of men, some perched on rooftops for a better view.
As she sits with her back to the crowd a bearded man is seen reading verses from the Koran condemning adultery, before saying: "We cannot forgive her, God tells us to finish her."
The video then shows a man in white being handed an AK-47 rifle. Some local reports said the shooter was the woman's husband but Khalid, the governor's spokeswoman, told AFP that he was a relative of the victim's husband.
The executioner approaches to within a couple of metres (yards) of the woman, says "Allahu akhbar" (God is great), and fires a total of 13 shots as the crowd cheers wildly, shouting "Long live Islam", "Long live mujahideen (holy warriors)".