An Iraqi firefighter douses fire of a car that exploded in the northern city of Kirkuk, 13 June 2006

Five bomb attacks in the northern Iraqi city of Kirkuk have killed at least 17 people.

Authorities say many of Tuesday's nearly simultaneous explosions were aimed at police, and several policemen are among the dead.

The bombings came a day after the terror group al-Qaida in Iraq named Abu Hamza al-Muhajer as its new leader, following the death of Abu Musab al-Zarqawi in a U.S. airstrike.

In an Internet posting Tuesday, the new insurgent leader vowed to continue attacks on U.S. forces in Iraq and their Iraqi allies.

The Iraqi government has announced plans for a security crackdown Wednesday in Baghdad that will involve at least 40,000 Iraqi and U.S. troops. The plan will include a curfew.

Also Tuesday, the chief judge in the trial of former President Saddam Hussein said he had heard the last defense witnesses.

Some information for this report was provided by AFP, AP and Reuters.