Militants attacked a military base in north Iraq, kidnapped 20 soldiers and later shot them dead, police and a morgue employee said on Sunday.
The soldiers were abducted by a large group of militants in several vehicles from a small base in the Ain al-Jahash area south of Mosul late on Saturday night, and their bodies found nearby an hour later.
Militants opposed to the Iraqi government frequently target members of the security forces, but it is rare for such a large number of soldiers to be kidnapped at once, especially from a military position.
The killings come as Iraq suffers a protracted surge in bloodshed, the worst to hit the country since the brutal sectarian fighting that peaked in 2006-2007 and killed tens of thousands of people.
The government has repeatedly blamed the unrest on external factors such as the civil war in neighbouring Syria.
But analysts and diplomats say widespread anger in the minority Sunni Arab community over alleged mistreatment at the hands of the Shiite-led authorities has also played a major role in the violence.