The bodies of nine Iraqi soldiers, all shot execution-style, were discovered in the northern city of Mosul (search) on Saturday, the U.S. military said.

The discovery came on top of four beheaded bodies that the U.S. military reported on Saturday that troops had found several days earlier. Those four bodies were still being identified.

U.S. forces found the nine soldiers' bodies off a main road about a mile from the Tigris River after getting a tip from the Iraqi National Guard (search), said Lt. Col. Paul Hastings of Task Force Olympia.

The men, who were not in uniform, have been identified as members of the Iraqi regular army based at the al-Kisik military base about 30 miles west of Mosul, near Tal Afar, he said.

All nine had been shot in the back of the head, Hastings said.

Mosul, Iraq's third largest city with around 1 million people 225 miles northwest of Baghdad, has been a focus of violence the past week. U.S. and Iraqi troops began a major military operation Tuesday after insurgents launched an uprising, taking control of some parts of Mosul and storming police stations.

The four other bodies were found Thursday. Three of the bodies were found by the roadside in a northeastern neighborhood of Mosul, while the fourth was discovered in the southwestern part of the city, Hastings said.

On Friday, a statement posted on an Islamist Web site in the name of Jordanian terror leader Abu Musab al-Zarqawi's (search) group said it had "slaughtered" two Iraqi National Guard officers "in the presence of a big crowd" in Mosul. The claim included no photos or video and could not be verified.

An extremist group, the Ansar al-Sunnah Army, announced in Web statement Saturday that it kidnapped and killed two members of a Kurdish political group in Mosul. It posted a video showing two men being shot. The men wore robes with the initials of their group, the Kurdistan Democratic Party, on them.

The claim's authenticity could not be verified, and it was not immediately known if there was any connection to any of the bodies found.