(AP Photo/K.M. Chaudary)
A militant spokesman defended the punishment, fueling a furor that cast more doubt on a creaking peace deal in the Swat valley that U.S. officials fear has created another haven for allies of al-Qaida.
Officials vowed to impose Islamic law, or Shariah, in Swat in February to halt 18 months of terror and bloody fighting between militants and security forces that killed hundreds of people.
Shariah has not yet formally been introduced, and provincial officials say that, in any case, they would not condone such whippings or the harsh brand of Islamic law practiced under Afghanistan's former Taliban rule. But the video provided a reminder of how hard-liners in control of much of valley interpret Islamic strictures.
Though it was unclear when and where the video was shot, it was believed to have been taken with a mobile phone in the Swat valley. It was broadcast widely Friday on Dunya TV and other Pakistani television stations.
The embattled government of Pakistan's North West Frontier Province struck the deal with a hardline cleric who helped secure a cease-fire. However, President Asif Ali Zardari's office says he won't sign the bill introducing Islamic law there unless he is satisfied that peace has been restored -- a prospect that seemed to recede Friday after a sharp outcry by rights groups.
"It is not a peace accord in Swat, instead it is a surrender by the government of Pakistan," said Asma Jehangir, head of Pakistan's main human rights organization. The flogging "is against all the women of Pakistan."
Prime Minister Yousuf Raza Gilani said the government remained committed to reconciliation in Swat but warned that it would restart the military operation if its authority was challenged.
The two-minute video, widely aired on local television Friday, shows the woman face down on the ground with two men holding her arms and feet. Her all-enveloping burqa has been hitched up to expose a pair of pink trousers.
A third man in a black turban with a long beard whips her backside more than a dozen times, causing her to scream repeatedly and shout "Stop it, stop it! It is painful!" A crowd of men watches silently in the background.
It was unclear who ordered the lashing and when it occurred.
Muslim Khan, spokesman for the Swat Taliban, said the militants publicly flogged a woman nine months ago over allegations that she had an illicit relationship with her father-in-law, but he was not sure if the video showed that incident.
He defended the punishment, although he said it should not have been done in public and should have been carried out by a boy who had not yet reached puberty.
Provincial government spokesman Mian Iftikhar Hussein said the incident occurred Jan. 3 -- before the peace agreement was signed. Some regional officials and the Taliban spokesman suggested the release of the video was an attempt to sabotage the agreement.
"The Shariah regulation in no way is going to allow this thing to happen at all," provincial Law Minister Arshad Abdullah said. "Let's not judge our deal by this video."
A spokesman for Zardari, the widower of slain former leader and women's rights torch bearer Benazir Bhutto, described the flogging as "barbarism" that should not be tolerated.
spokesman Farhatullah Babar said Zardari had ordered authorities to apprehend those responsible -- a near-impossible task in a zone from which the police and moderate tribal leaders have fled in fear.
Pakistan's recently restored chief justice also opened an inquiry, saying the case represented "a serious violation" of the law and fundamental rights.
Iftikhar Mohammed Chaudhry, who had been removed by former military ruler Pervez Musharraf in part for pursuing human rights cases, ordered security officials to produce the victim in the Supreme Court in time for a hearing on April 6.
U.S. officials have criticized Pakistan for striking a series of usually short-lived peace deals with militants, arguing that they give extremists time to regroup and focus on launching cross-border attacks against U.S. and NATO troops in Afghanistan.
They have expressed concern about the accord in Swat, but are also pressing Pakistan's army to switch its focus to al-Qaida strongholds closer to the Afghan border.