The report said there has been no satisfactory investigation into allegations by some family members and lawmakers that Ozal, whose pro-Western policies helped modernize Turkey and gave the U.S.-led coalition a strategic ally during the Persian Gulf War, might have been poisoned.
The report by the State Auditing Board, which is under the direct supervision of President Abdullah Gul, cautioned that most of the allegations were "intangible," but suggested an autopsy and a hair sample test could confirm for certain the cause of death. It said the results of the president's blood tests, as well as his blood samples, were missing.
Doctors at the time said Ozal, who underwent triple bypass surgery in 1987, died of heart failure on April 17, 1993.
But, the president's wife, Semra Ozal, has claimed she received a note in 1998 that said her husband was poisoned and has told several television stations that Ozal died a day after drinking lemonade at a reception in Ankara. The report said Ozal apparently consumed fresh orange juice but not lemonade at the event.
The report said the burial of the president without an autopsy has also fueled concerns over his death. It cited inconsistent statements by officials about how and when his health deteriorated.
Conflicting statements and the questions over the fate of the blood tests showed that "the death of late Turgut Ozal was still a mystery today," according to the report.
Ozal, who is of Kurdish origin, was allegedly preparing to announce a plan to reconcile with the Kurdish minority as a war by Kurdish rebels for autonomy in the largely Kurdish southeast reached its peak.
Associated Press writer Emrah Betos contributed to this report.