CACI limited have claimed that allegations of torture, abuse and war crimes said to have been carried out by its employees at Abu Ghraib cannot be confirmed, and that none of their employees ahd ever been charged with any wrongdoing.

The denial comes as the Crown Office have ruled out bringing a prosecution against the company - recently awarded the Scottish census contract for 2011- citing a lack of jurisdiction, notwithstanding the historic Gecas case brought against a Lithuanian national accused of war crimes who had relocated to Edinburgh. That case ultimately did not proceed due to insufficient evidence to warrant a prosecution under the War Crimes Act.

"In August 2003, CACI International Inc provided staff to the US Army to conduct IT and intelligence work in Iraq including interrogation services," the firm said in a statement.

"Subsequently, in Spring 2004 an allegation was made that a CACI employee had been involved in the mistreatment of detainees at the Abu Ghraib prison in Iraq. Both CACI and the US government conducted extensive investigations into the allegation but could not confirm it. Over five years on, the allegation remains unproven and no CACI employee has ever been charged with any wrongdoing.

"CACI have always taken this allegation extremely seriously. CACI do not condone, tolerate or endorse any illegal behaviour by its employees in any circumstances or at any time. If an employee of CACI had been found to be involved in such behaviour we would have taken swift and appropriate action. We have, and always will, hold ourselves to the highest ethical standards."