The US military has revealed that five separate investigations are under way into abuse of Iraqi prisoners.
These centre on the handling of detainees and their interrogation at the Abu Ghraib prison outside Baghdad.
The admissions follow the release of photographs featuring abuse (AP/Courtesy The New Yorker)
Amid the worldwide furore sparked by the publication of photographs showing US soldiers subjecting Iraqi prisoners to humiliation and psychological torture, the Pentagon also said there were separate inquiries into a number of deaths of detainees in Iraq and Afghanistan.
Britain is also looking into abuse allegations after the publication of photographs which apparently show UK troops mistreating Iraqi prisoners, though there are concerns that they may be faked.
Pentagon officials say five inquiries into the "heinous" acts at Abu Ghraib have been launched since a soldier first reported the abuses to his superiors on 13 January.
- A criminal investigation into the soldier's claims was ordered by the US commander in Iraq, Lt Gen Ricardo Sanchez on 14 January.
- Maj Gen Antonio Taguba began a broader, administrative investigation of procedures at Abu Ghraib on 31 January.
- In February, the US army's inspector general's office started an assessment of military detention operations around the world, examining the general operations doctrine and training.
- Commanders of the army reserve launched an investigation into the training of reservists - many of whom serve in Iraq - with emphasis on military police and military intelligence activities related to prisoners.
- Gen Sanchez ordered another inquiry on 23 April where Maj Gen George Fay will look into military intelligence practices in Iraq and whether personnel were involved in abuse.
In a related move, the navy's inspector general started an assessment this month of detainee operations at the Guantanamo Bay prison camp in Cuba and the navy brig in Charleston, South Carolina where terror suspects are held.
As a result of the first inquiry into the soldier's allegations, which are believed to include the abuses photographed in Abu Ghraib, US defence officials say six soldiers from the 800th Military Police Brigade have been charged with criminal offences.
The two sergeants and four enlisted troops are still serving in Iraq - though not as military police. They will face courts martial on charges including conspiracy, dereliction of duty, cruelty and maltreatment, assault and indecent acts with another, the Pentagon says.
Six other soldiers were reprimanded, including a battalion commander and battalion operations sergeant who were relieved of duty immediately, Defence Secretary Donald Rumsfeld said.
TAGUBA REPORT FINDINGS
Detainees threatened with loaded pistol
Inmates beaten and sexually abused
Prisoners photographed in sexual positions
Detainees threatened with dogs
Senior army official Gen George Casey said there had as yet been no charges against military intelligence officers who may have been involved in the abuse, which President George W Bush and others accept did occur.
The broader review by Gen Taguba, which is reported to have found compelling evidence of "sadistic, blatant, and wanton criminal abuses", was completed in March.
While military chiefs say "everyone" knew of its findings almost immediately, the lengthy report was submitted up the chain of command in the usual measured way so two months later it had not been read by Mr Rumsfeld or the US' top officer, Gen Richard Myers, the chairman of the Joint Chiefs of Staff.
US media say the Taguba report mentions possible involvement in the prisoner abuse by civilian contractors working for the intelligence services.
The Virginia-based CACI International company, which provides information technology and interrogation services to the US defence department, says it has not been informed officially that its employees may have been involved.
Its chairman, Jack London, said he had read the allegations in leaked versions of the Taguba report concerning two of the company's men.
But he said CACI had not been told of the claims officially and so all employees were still in their jobs in Iraq.
Civilians - this time working for the Central Intelligence Agency - are also being investigated in relation to deaths of prisoners in Iraq and Afghanistan.
Defence officials said there had been 25 deaths of prisoners in Afghanistan and Iraq since December 2002. Twelve were considered to be from natural or undetermined causes, one was considered justified homicide, two were murder and 10 are still being investigated.
A soldier who shot dead an Iraqi prisoner who was allegedly throwing stones was found guilty of murder at a court martial, reduced in rank and discharged. He did not serve any time in prison.
In the other established case of homicide, the conduct of a CIA interrogator has been referred to the US justice department for possible criminal prosecution.
Reports indicate that independent contractors working for the CIA are also involved in two other suspicious deaths in custody - one in Iraq and one in Afghanistan.
Investigations are continuing into the open cases involving deaths and at least 10 assaults on detainees.
The UK Armed Forces Minister, Adam Ingram, vowed on Tuesday that "no stone will be left unturned" in an investigation into photos showing apparent abuse by British troops in Basra which were published in the Daily Mirror newspaper.
The special investigation branch of the Royal Military Police has launched a three-pronged inquiry, following up lines of investigation in the UK, Iraq and Cyprus where the suspected perpetrators are based with the 1st Battalion, the Queen's Lancashire Regiment .
Mr Ingram also revealed that 33 cases of civilian deaths, injury or mistreatment in Iraq had been the subject of military investigations. Fifteen of the 21 inquiries completed had found there was no case to answer, while possible action was being considered in six cases.