Three US soldiers have been killed by a roadside bomb north of the Iraqi capital Baghdad.
A military vehicle was destroyed in the blast that occurred at around 6 a.m. Irish time near the town of Samarra, 100 km north of Baghdad, a military statement said.
Earler, a suicide car bomb exploded outside a government building in the Kurdish city of Arbil in northern Iraq, killing at least four people and wounding 20, Iraqi officials said. The car detonated just outside the gates of the Interior Ministry in the city, killing the bomber, two policemen guarding the facility and a passer-by.
The ministry building suffered material damage and windows of nearby residential buildings were shattered by the blast, witnesses said.
US-led occupation forces in Iraq have tightened security in Baghdad and other hotspots in anticipation of attacks by insurgents to coincide with the holiday season.
The mainly Kurdish north has seen less violence than the rest of Iraq since US-led forces deposed Saddam Hussein in April, but several car bombs have targeted US troops and Iraqis working with them in the region.
Arbil was the seat of an autonomous Kurdish government after the 1991 Gulf War when US-backed Kurds rebelled against Saddam's government in Baghdad.