IMAGES from a leaked police video of the Port Arthur massacre have been placed on the internet by pro-gun campaigners.

Supporters of those responsible for posting the images last night defended the action as necessary to expose an alleged police cover-up.

Graeme Scurr claims his wife, Wendy, a former worker at the historic Tasmanian site, was given the tape - which was labelled as a police training video - by someone who bought it at a Hobart tip for 10 cents.

The video includes harrowing images from the 1996 massacre at Port Arthur, in which gunman Martin Bryant killed 35 people.

Tasmanian Police Commissioner Richard McCreadie expressed concern yesterday that placing images on the internet had the potential to cause immense distress to survivors of the shootings and victims' families.

"Any person who copies or distributes the video in any form is liable to action under the Copyright Act," he said.

But within hours of his warning, The Australian learned that stills of at least two images purported to have been taken from the video had been posted on the net by a pro-guns campaigner.

One of the images has a white rectangle with the words "body of victim" pasted over what appears to be a body-bag.

It emerged last night that the vice-president of the Firearm Owners Association, Queensland-based Ian McNiven, has a copy of the tape, supplied to him by the Scurrs, who are understood to have made three other copies.

Mr McNiven said last night the Scurrs shared his belief that Bryant had an accomplice and that this had been covered up by police.

They had given him a copy of the video "for safekeeping" and he believed it showed several inconsistencies between evidence made public by the Tasmanian police and the actual events.

"People shouldn't have a go at me for having it on the net ... they should be squarking about the competency of Tasmania police," he said.

Mr McNiven insisted he had not put the images on the website, and said he would not reveal the name of the person who had.

Mr McCreadie said the video contained material that was never intended to be in the public domain.

"In an attempt to address any concerns of victims that may have arisen during this matter a dedicated telephone number has been established for them to contact to be provided with more information," he said.