BAGHDAD (AP).- Authorities in northern Iraq have arrested three men on charges they were trying to traffic stolen antiquities, including the bust of a Sumerian king, a local army commander said Saturday.

The three were arrested in a sting operation after attempting to sell one of the artifacts for $160,000 to an undercover intelligence officer of the Iraqi Army's 12th division in a village southwest of Kirkuk, division commander Maj. Gen. Abdul Amir al-Zaidi told reporters.

The sting operation, which took place around two weeks ago, was set up based on intelligence from local residents, he said.

"The duty of Iraqi army is not only to chase the terrorists but also to protect state treasures," he said.

In total the men had eight pieces from the Sumerian period, which dates from around 4000 B.C. to 2000 B.C., that they were trying to sell.

A fourth man is still being sought in the case, al-Zaidi said. He gave no further details.

It was not clear where the items came from, but after the fall of Saddam Hussein's government, looters stole and smashed priceless treasures from the National Museum in Baghdad and other museums and libraries. At the time, Iraq's museums held priceless, millennia-old collections from the Assyrian, Sumerian and Babylonian cultures that chronicled some 7,000 years of civilization in ancient Mesopotamia.

Some have been recovered but many remain missing.

Elsewhere in Iraq on Saturday, a roadside bomb killed an 11-year-old boy and wounded his two friends in the violence-plagued northern city of Mosul.

The bomb exploded around 4 p.m. after a police patrol that was the apparent target had already passed by, a Mosul police officer said. He spoke on condition of anonymity because he was not authorized to talk to the media.

An off-duty Iraqi soldier was also killed in Mosul in a drive-by shooting, he said.

Mosul is in an area rife with tension between Arabs and Kurds over territory.

The U.S. military says it is also the last urban battleground of al-Qaida in Iraq and other Sunni extremist groups. The level of violence there remains high even as it has dropped elsewhere in Iraq.