An Iraqi detainee has died of an apparent heart attack in Camp Bucca, a US-run prison in southern Iraq, the US military said on Saturday.
"The detainee was admitted to the hospital on October 5 after complaining of chest pains," the military said in a statement.
In the early hours of Thursday morning he called for assistance.
"Doctors in the intensive care unit attempted to assist him in breathing; however, a cardiac monitor showed no pulse," the statement said.
"Further attempts to resuscitate the detainee failed."
According to standard procedures, an autopsy will be conducted to determine the cause of death.
The dead prisoner was not identified.
Some 13,000 detainees are held in prisons run by the coalition forces in Iraq, including many elderly figures who were prominent in ousted dictator Saddam Hussein's former regime.
Camp Bucca, located near Umm Qasr in the extreme south of Iraq, is one of three remaining coalition-run prisons, the others being Camp Cropper near the Baghdad airport and Camp Suse in the north near Sulaimaniyah.