Pakistan Police on Monday said Taliban militants have released footage that appears to show the execution-style killing of 16 policemen in the country's tribal north-west.
In the video, the policemen are lined up on a hillside, with their hands tied behind their backs, standing in front of a group of gunmen, who fire on them. The killers' faces are concealed by scarves.
The Associated Press reported that one of the militants accused the men of shooting dead six children in the Swat Valley, which was once controlled by the Taliban.
The bodies were discovered by locals once the militants had left.
A Pakistan army spokesman told the BBC the video, posted on LiveLeak, looked to be authentic.
A note attached to the video said the execution took place in June, when militants from Afghanistan's eastern Kunar province crossed the border into Pakistan's Dir district and captured the police.
Pakistan has complained in the past that Afghan and NATO forces are not doing enough to stamp out the Taliban in Kunar, where the U.S. has withdrawn most of its forces.
But Afghanistan and the U.S. blame Pakistan for not getting rid of insurgent havens on its side of the border.