Gunmen attacked a police checkpoint in west of Baghdad on Sunday, killing four policemen, a provincial police source said.

Unidentified gunmen stormed a police checkpoint early in the morning in Abu Ghraib area, some 25 km west of Baghdad and killed four policemen before they fled the scene, the source told Xinhua on condition of anonymity.

Iraqi security forces cordoned off the area and sealed off the scene, as the police was investigating the incident, the source said.

Abu Ghraib area is including the village of Zauba which was the scene of another deadly attack in mid November, when gunmen disguising in army uniforms stormed the village and conducted a search operation, detaining 13 villagers and executing them just outside the village before they fled the scene.

Sporadic attacks continue in Iraq as part of recent deterioration in security which shaped a setback to the efforts of the Iraqi government to restore normalcy in the country ahead of the country's national elections early next year.