UK soldiers in Iraq could suffer the consequences as images of troops allegedly abusing Iraqi civilians are beamed around the world, it is feared.
The court was shown 22 photos depicting alleged abuse
The Conservatives and Liberal Democrats said the photographs could lead to a backlash as Iraq's elections loom.
The pictures emerged on Tuesday at a court martial where three Royal Regiment of Fusiliers soldiers are facing nine charges.
One has admitted one assault charge, but all other charges are denied.
Twenty-two photographs released by the court martial include images of naked Iraqis apparently simulating sex acts.
The Tory's shadow defence minister, Keith Simpson, said he was "horrified" by the images.
He said the vast majority of the British military would regard them as "obscene" and they would "realise the impact in Iraq".
Liberal Democrat deputy leader Sir Menzies Campbell said: "The task of British forces in the difficult and sensitive run-up to the election on 30 January will be made more difficult by publication of these photographs.
"These pictures will inevitably open old wounds and be part of drawing parallels with Abu Ghraib."
On Tuesday the head of the British Army, Gen Sir Mike Jackson, condemned abuse but would not comment on the pictures.
One image shows a soldier aiming a simulated punch at a detainee
He stressed that only a "small number" of the 65,000 British troops who had served in Iraq had been accused of any mistreatment.
L/Cpl Darren Larkin, 30, from Oldham, Greater Manchester, admitted one charge of assaulting an unknown man in May 2003, but denied another charge.
Cpl Daniel Kenyon, 33, and L/Cpl Mark Cooley, 25, from Newcastle upon Tyne, entered not guilty pleas at the court martial in Osnabruck, Germany.
The offences the soldiers are charged with are alleged to have taken place at a Basra aid camp, known as the Bread Basket, on or around 15 May 2003, weeks after coalition troops had ousted Iraqi dictator Saddam Hussein's regime.
The three soldiers are accused of abusing looters who were being detained at the camp in southern Iraq after attempting to steal powdered milk and food.
The charges also include two relating to the alleged placing of a detainee on the forks of a forklift truck.
Cpl Kenyon was described as a "war hero" who had saved several lives by his defence counsel on Wednesday.
Cpl Kenyon, centre, and L/Cpl Cooley, right, deny the charges
Joseph Giret told the court the accusations against Cpl Kenyon stemmed from orders given by his commanding officers.
Camp commander Maj Dan Taylor is due to give evidence on Wednesday.
He had ordered his soldiers to "work hard" any looters they captured, the court martial heard on Tuesday.
Lt Col Nick Clapham, prosecuting, told the hearing that order was in breach of the Geneva Convention.
If found guilty, the trio, who are stationed at a British army base in Osnabruck, northern Germany, could be jailed and discharged from the army.
They are being tried before Judge Advocate Michael Hunter and a panel of British officers.
The court martial, expected to last three to four weeks, comes just days after a US soldier was sentenced to 10 years in jail after he was found guilty of abusing prisoners at Abu Ghraib jail, near Baghdad.