Gunmen in army uniforms kill 12 Iraqi villagers

* Village once seen as Sunni insurgent hotbed

* Tribal conflict may be motive for attack

(Adds statement, details)

BAGHDAD, Nov 16 (Reuters) - Gunmen wearing military uniforms shot dead at least 12 men in a pre-dawn attack in a village near Baghdad on Monday, villagers and police said.

The attack took place in the mainly Sunni village of Zauba, west of Baghdad, which at the height of the fighting in Iraq was viewed as a hotbed of support for Sunni Islamist insurgents.

One of those killed was affiliated with the main Sunni Arab political party, the Iraqi Islamic Party, police said. Villagers said some were members of formerly U.S.-backed neighbourhood militias that turned on al Qaeda.

The office of the spokesman for security in Baghdad, Major General Qassim al-Moussawi, said 13 people had been killed.

"Our initial information suggests this occurred because of a tribal conflict," the office said in a statement.

The violence triggered by the 2003 U.S. invasion has fallen off over the past 18 months but shootings, bombings and other attacks are still common. (Writing by Deepa Babington; Editing by Kevin Liffey)