Doubts have been raised over the authenticity of the photos published in the Daily Mirror, which purportedly show an Iraqi captive being beaten by British troops.
The BBC quoted anonymous sources close to the regiment as saying that the gun held by a soldier in the pictures was the wrong type of SA-80 rifle and lacked the sling with which it would be worn by serving troops.
A hat seen in the pictures was not of the sort worn by members of the regiment in Iraq, the sources claimed.
The truck in which the scenes took place appeared to be of the wrong type and the alleged victim showed no signs of the sweat, dirt and injuries that could be expected in an arrest followed by violent interrogation, the sources added.
The British Foreign Secretary Mr Jack Straw has acknowledged that Britain may find itself facing claims for compensation if allegations that its troops abused Iraqi detainees are proved to be true.
However, Mr Straw stressed that the Royal Military Police investigation into the photographs was at a very early stage and that no final judgement on the "awful" scenes depicted had yet been reached.
The Mirror newspaper said they had been received from two soldiers in the Queen's Lancashire Regiment who were horrified at the brutality of a "rogue element" in the Army occupying southern Iraq.
The paper was standing firmly by its story, which alleged that the Iraqi man had been subjected to an eight-hour beating, during which he was urinated on and had his jaw broken and teeth smashed before being dumped from a moving vehicle.
A spokeswoman for the paper said: "We've carried out extensive checks to establish the veracity of the photographs and have no doubts about their authenticity."
Defence sources made clear that the RMP investigation would inevitably involve checks on whether the photos were genuine. But there were no official indications that the inquiry had yet uncovered any reason to doubt them.
Meanwhile, a serving officer claimed that mistreatment of prisoners by British troops was not unheard-of in Iraq and that he was "certain" that brutality like that seen in the photographs had taken place.
PA