(Adds Dannatt quotes in paragraphs 7-10)

By Peter Graff

LONDON, April 30 (Reuters) - Britain's first convicted war criminal was sentenced to one year in jail on Monday for mistreating Iraqi prisoners in a case that exposed senior commanders to accusations they had authorised abuse.

Corporal Donald Payne was also kicked out of the army, becoming the only British soldier punished in the case of Baha Musa, an Iraqi hotel receptionist who died after suffering 93 injuries from beatings while in British custody in 2003.

His lawyer called him a "sacrificial lamb", punished for carrying out orders.

Payne had entered his guilty plea to the war crime of abusing prisoners at the start of an eight-month trial that then failed to secure convictions against six others, including his unit commander, Lieutenant Colonel Jorge Mendonca.

During the trial, witnesses testified that abuse of prisoners had been authorised by the British brigade headquarters in Iraq, which allowed detainees to be "conditioned" with harsh treatment such as stress positions.

Britain has denied its commanders authorised such techniques, which it considers illegal. But the judge ruled Mendonca and his staff were not to blame because they believed their own commanders had approved the abuse.

MORE CHARGES POSSIBLE

The army's head said more charges could still be issued.

"The end of this trial does not mean that this incident is now closed. We know how Mr Baha Musa died, but we do not yet know who was responsible," Chief of the General Staff Sir Richard Dannatt said in a statement.

"It has always been our policy that all British military personnel deployed on operations must be in no doubt about their duty to behave in accordance with the law. It now appears that this duty was forgotten or overlooked in this case."

Britain's military has come under fire for failing to secure convictions in cases of abuse in Iraq. Two other trials of British troops over the deaths of Iraqi prisoners collapsed after months of testimony and millions of pounds spent.

Musa was part of a group of Iraqi detainees who were kept blindfolded and beaten throughout 36 hours in detention.

The judge ruled that prosecutors had failed to identify who was behind the beatings because of an "obvious closing of the ranks" among soldiers who refused to testify against their comrades. The surviving victims were hooded when they were abused and could not identify who beat them.

The judge threw out manslaughter charges against Payne, who was restraining Musa when he died. But Payne had already pleaded guilty to the lesser abuse charge, making him Britain's first official war criminal.

AlertNet news is provided by