The new total released by the Pentagon on Monday mentions at least two more deaths than previously disclosed.
The new figures comes after Human Rights Watch (HRW) sent a letter to US Defence Secretary Donald Rumsfeld demanding that Washington "get serious about prosecuting people implicated in prisoner deaths and mistreatment".
Investigations in at least three of the deaths are ongoing, according to the list drawn up by Chris Grey, spokesman for the US Army Criminal Investigation Command (CID).
Previously unreported cases included the death of an A Wahid in November 2003.
"CID investigation closed and completed report forward to command," the list said, referring to Wahid. "Case involved other than US personnel, and Afghan law enforcement officials have been notified."
A senior army official said the case involved the death of a prisoner who was already seriously injured when he was left at the gate of a US base by an Afghan militia, and who later died in US custody.
A second previously unreported case dates from January 2003, according to the list. "Death investigation of person detained by US soldiers in Wazi village in January 3," it said. "Case remains ongoing."
Because the case is still under investigation, defence officials would provide no additional information.