BAGHDAD - Four Iraqi policemen were killed and five others wounded in two attacks on Thursday morning, an Iraqi Interior Ministry source said.

An Iraqi soldier guards at a checkpoint during curfew in the restive city of Baquba. [AFP]

Unknown gunmen opened fire from their machine-guns at about 7: 00 a.m.on a police patrol in the Industrial Street in the Elwiyah neighborhood, the source told Xinhua on condition of anonymity.

Three policemen were killed and another was wounded in the attack, the source added.

In a separate incident, the US troops opened fire at 7:30 a.m.on policemen affiliated to the Facilities Protection Force who was guarding an under construction building in eastern Baghdad, the source said.

One policeman was killed and four others were wounded, he said, adding that it was not known why the US troops fired on the guards.

The US military did not confirm the incident at the time being.