The Daily Mirror has insisted photos of British soldiers abusing an Iraqi prisoner are genuine but army sources say they are still not convinced.
The Mirror has rejected allegations the pictures were fake
The newspaper has also printed more allegations, claiming soldiers have swapped hundreds of photos showing brutality against Iraqi captives.
The Queen's Lancashire regiment say questions about the authenticity of the original photos remain unanswered.
They highlight discrepancies in the soldiers' clothing and equipment.
Doubts originally surfaced over the weekend about photos published in Saturday's Mirror appearing to show a hooded man being struck with a rifle butt, urinated on and having a gun held to his head.
The paper says the sources for its photos are two members of the Queen's Lancashire Regiment who are standing by their account of what happened.
One of the unnamed soldiers said: "Maybe the officers don't know what is going on - but everybody else does. I have seen literally hundreds of pictures.
"The Army knows a lot more has happened."
However a source close to The Queen's Lancashire Regiment told the BBC their questions about the photos had not been answered by the Daily Mirror "to any degree of satisfaction whatsoever".
The regiment says the soldiers in the photos are not their troops, and adds the uniforms in the pictures are not of a type worn by them in Iraq.
A spokesperson for the newspaper acknowledged the regiment's statement but said the Mirror stood firmly behind their sources.
The images have already been seen in the Middle East
She said: "Although we appreciate that the Queen's Lancashire Regiment has concerns, as they put it, about the Daily Mirror, we also have very serious concerns about the behaviour of some of their troops in Iraq."
Liberal Democrat leader Charles Kennedy said that even if the photos were proven as fakes, the fallout in the Arab world would be "massive."
Speaking to BBC Radio 4's Today programme, he said: "Whether true or false, there is no doubt whatsoever they are going to have a massive impact in terms of domestic opinion within Iraq and again across the Muslim world and the Arab world as a whole."
Mr Kennedy said they could act as further confirmation of "their worst
assumptions about us".
The two soldiers who gave these images to the paper say they represent only the tip of the iceberg.
In Monday's Mirror the soldiers, who wish to remain anonymous, claim many pictures were destroyed in September when the troops' luggage was searched as they left Iraq.
They also detail other alleged incidents of brutality towards local people, including a baton attack which left a prisoner with a compound fracture to his arm.
A Ministry of Defence spokesman said the authorities were not aware of other
photos of prisoners being mistreated or of a culture of trading pictures.
The MoD spokesman was unable to confirm reports the regiment was given a dressing down in their Cyprus base by a senior officer.
An investigation has already begun into the claims, also carried in the Mirror, that British troops assaulted the prisoner pictured in the paper, before throwing him from a lorry.
BBC defence correspondent Paul Adams said sources close to The Queen's Lancashire Regiment were suspicious about the authenticity of the photographs questioning whether the rifle, hats and truck pictured matched those issued to men in Iraq.
And they asked why there appeared to be no sign of sweat, dirt or injuries on the body of the alleged victim.