With just four days until the United States transfers power to Iraq's interim government, insurgents are on the offensive sparking a fresh wave of violence across Iraq.

In Baquba, north of Baghdad, insurgents attacked the offices of a major Shi'ite political party and blew up the local headquarters of Iraq's interim prime minister. At least three people were killed.

Further to the north, in the mainly Kurdish city of Arbil, a car bomb exploded killing one person and injuring at least 18.

While to the south, in the Shi'ite holy city of Najaf, which has been quiet for several weeks, militiamen loyal to radical Shi'ite cleric Moqtada al-Sadr opened fire on a coalition convoy.

And a U.S. soldier was killed after his patrol came under attack in central Baghdad.