Three British soldiers faced a court martial accused of acts of abuse and assault against Iraqi civilians.
The charges include forcing detainees to strip and simulate sex acts. One of the soldiers is also accused of tying a prisoner to a forklift truck.
The alleged offences involved detainees at an aid camp known as Camp Bread Basket near Basra in southern Iraq.
Lance Corporal Mark Cooley (25), from Newcastle upon Tyne, and Corporal Daniel Kenyon (33), entered not guilty pleas to the charges as the court martial got under way.
Lance Corporal Darren Larkin (30), from Oldham, Greater Manchester, admitted one charge of assaulting an unknown male at the camp, but denied another charge.
The alleged offences took place in May 2003, just weeks after Saddam Hussein's regime was ousted by coalition troops.
The soldiers, all members of 1st Battalion The Royal Regiment of Fusiliers, were guarding the camp at the time. They are accused of abusing looters who broke in and attempted to steal food and powdered milk. The court was due to be shown photographs of the alleged abuse.
The trio are stationed at a British Army base in Celle, northern Germany.
Their trial, which is expected to last three to four weeks, is taking place at a British Army-run court martial centre in the city of Osnabruck.
The soldiers face a total of nine charges between them. Corporal Kenyon faces six charges including two of aiding and abetting a person to force two naked males being detained by British troops to simulate a sex act.
Lance Corporal Cooley faces three charges including tying an unknown male prisoner to a forklift truck as well as punching and kicking another unknown male also being detained by the Army.
Lance Corporal Larkin denies one charge of disgraceful conduct of an indecent kind by forcing two unknown Iraqi males to undress in front of others.
AP