The Pentagon released a list of the death cases investigated in Afghanistan after Human Rights Watch sent a letter to US Defence Secretary Donald Rumsfeld demanding that the United States "get serious about prosecuting people implicated in prisoner deaths and mistreatment."

Investigations in at least three of the deaths are still ongoing, according to the list drawn up by Chris Grey, spokesman for the US Army Criminal Investigation Command.

Previously unreported cases included the death in November 2003 of an individual identified as A. Wahid.

"CID investigation closed and completed report forward to command," the Army Criminal Investigation Division (CID) statement said. "Case involved other than US personnel, and Afghan law enforcement officials have been notified."

A senior army official said the case involved a prisoner who was already seriously injured when he was left at the gate of a US base by members an Afghan militia. The prisoner later died in US custody.

A second previously unreported case dates from January, 2003, according to the CID tally.

"Death investigation of person detained by US soldiers in Wazi Village in January 03," it said. "Case remains ongoing."

Because the case is still under investigation, defence officials would provide no additional information.

The CID list shows that yet another prisoner, identified as M Sayari, died in military custody on August 28, 2002. It would be the earliest known death of a prisoner in US military custody. The CID said the case was adjudicated by the army, but offered no other information.