Pentagon investigates claims that élite Delta Force abused detainees

The investigation into the torture and mistreatment of Iraqi prisoners has been extended to include allegations that the US army's élite Delta Force was involved in some of the worst abuses carried out by American troops.

The investigation into the torture and mistreatment of Iraqi prisoners has been extended to include allegations that the US army's élite Delta Force was involved in some of the worst abuses carried out by American troops.

Reports say the Pentagon's inspector general is investigating the alleged abuse, said to have taken place at a secretive detention camp, or Battlefield Interrogation Facility, near Baghdad airport, known simply as the BIF.

If the allegations are true they would further rock the Bush administration and shock the US public, already reeling from the seemingly endless stream of photographs and witness statements detailing widespread abuse of prisoners at the notorious Abu Ghraib jail and elsewhere in Iraq. The covert Delta Force, known for its use in special operations and rescue missions, is the equivalent of Britain's SAS and is a source of pride to many Americans.

The Pentagon has declined to comment on the allegations, but according to two senior US officials quoted by the NBC television network, the Delta Force facility is the scene of "the most egregious violations" of the Geneva Conventions in all of Iraq's US-run prisons. It is not known whether the facility is still operating.

The officials said that from the moment the prisoners enter the BIF they are hooded and kept in tiny cells. In the six interrogation rooms, the special forces soldiers routinely drug prisoners, hold a prisoner under water until he thinks he is drowning or smother him almost to the point of suffocation.

The US Defence Secretary, Donald Rumsfeld, has said that while Washington does not believe the Geneva Conventions apply to stateless terrorists such as al-Qa'ida, prisoners from the war in Iraq are considered to be prisoners of war.

The new revelation emerged as the Pentagon announced it was investigating the deaths of at least nine more prisoners, bringing to 37 the number it has looked into in Iraq and Afghanistan. It said the deaths were being treated as homicides, which meant someone else was involved in the prisoners' deaths.

A 10th prisoner death has already been resolved. A soldier shot and killed a prisoner in Iraq who threw rocks at him in September 2003. The soldier was punished and dismissed from the Army.

Among the causes of death attributed to the nine new cases are "'blunt force injuries and asphyxia", ''asphyxia due to smothering and chest compression" and "multiple gunshot wounds".

One of the deaths being investigated is that of Major General Abed Hamed Mowhoush, a former commander of Saddam Hussein's air defences, who died in November 2003 during interrogation. It is understood his death, attributed to ''asphyxia due to smothering and chest compression", involved a CIA interrogator.

Of the 37 deaths that have been looked into, 32 took place in Iraq and five in Afghanistan. Some date back to August 2002. Most of the detainees died inside detention facilities, and around half of the deaths have been attributed to natural causes.