A head and body of an Asian-looking man, wrapped in two US flags, were revealed in Baghdad, Iraqi officials said.
However, they were unable to say immediately whether it was the remains of a 24-year-old Japanese backpacker Shosei Koda abducted in Iraq after he failed to find an affordable hotel accommodation.
According to Colonel Adnan Abdul Rahman, a spokesman for the interior ministry, the decapitated body was retrieved behind the al-Karma hospital, near to Haifa Street, a notorious area in the centre of Baghdad.
Shosei Koda was threatened with beheading by Islamic militants unless Japan pulled its military from Iraq by late Thursday. Tokyo refused to withdraw its 550 troops stationed in Iraq on a humanitarian mission, the first one abroad since the World War II.