Pakistan army says 'extra-judicial killing' video faked
Pakistani military officials have dismissed as fabricated a video purporting to show a firing squad of uniformed soldiers shooting dead young men who were blindfolded and bound.
The video's authenticity cannot be verified, and it is unclear when or where it was filmed.
Human rights groups say they have previously documented extra-judicial killings by Pakistani troops, but they cannot vouch for the video.
The military says it is investigating.
"No Pakistani Army soldier or officer has been involved in activity of this sort," army spokesman Maj Gen Athar Abbas told the BBC.
US voices concern
The individual who sent it to the BBC said many people in the Swat valley had the clip on their phones.
However journalists in Swat have told the BBC that the first they heard of the video was when it was reported in the New York Times two days ago.
It shows men in military clothing pushing a group of young men one by one through a forest.
Eventually, six men - all in traditional civilian clothing - are lined up, blindfolded and with their hands tied behind their backs.
At least seven of the men in military clothing then form a line and raise their weapons. After what sounds like a sustained burst of gunfire, the men in civilian clothing then crumple to the forest floor.
In 2009, the Pakistani military mounted an offensive to drive Taliban militants out of the Swat valley.
Human rights organisations have accused them of carrying out extra-judicial killings during this time.
"We have previously documented executions in Swat that are similar to what is depicted in this video," Ali Dayan Hasan, representative of Human Rights Watch in Pakistan told the BBC.
"Human Rights Watch cannot say anything about the authenticity of the video."
The US State Department says it has raised the issue with the Pakistani government.
Spokesperson PJ Crowley said the US took allegations of human rights violations" very seriously", and that the issue of extrajudicial killings had been a part of an "ongoing conversation" with Pakistan.
Pakistan has promised to take action if the video - which has also been circulating on YouTube - is authenticated.
"The army has a policy of zero tolerance on issues like this," Maj Gen Abbas said. "At this stage I can't comment about what action might be taken" if the video is real, he added.
Another military spokesman, Brigadier Syed Azmat Ali, said the video "could have been staged in five minutes".
Army uniforms are widely available in local markets, he said.
But Human Rights Watch has called for a full investigation.
"We have had such formulaic responses," Mr Hasan said. "But to date, there has been no action to hold military personnel accountable for well-documented abuses in counter-terrorism operations."