The US troops found 14 bodies buried in a mass grave near the city of Samarra, some 120 km north of Baghdad, a source from US and Iraqi liaison office said on Monday.
"The victims were men with their hands tied behind their backs and shot in the heads," the source from the Joint Coordination Center in the province told Xinhua.
The mass grave was found near a main road to the south of the city, an area which has long been under control of the al-Qaida militants, the source said.
Four bodies were also found scattered in the area, the source added.
The gruesome finding came as unconfirmed reports said that the Iranian President Mahmoud Ahmadinejad is planning to visit the city where two of the most revered Shiite Imams are buried.
On Sunday, Ahmadinejad started a landmark two-day visit to Baghdad, which is the first for an Iranian president since Iran's Islamic Revolution in 1979.
Violence persists in some Iraqi areas including Salahudin, shaping a setback to the security in the war-torn country after a relative lull of violence as a result of a US military surge.
(Xinhua News Agency March 3, 2008)