Suicide attacks kill dozens in Iraq (VIDEO)

Suicide bombers launched deadly attacks for a third straight day in Iraq, killing scores of Shiite pilgrims marching toward a Shiite shrine Thursday as well as a provincial police headquarters.

As many as 45 pilgrims were killed and 110 others wounded in two suicide bomb attacks in the holy Shiite city of Karbala, south of Baghdad.

Earlier in the day, two Shiite pilgrims making a three-day trek by foot to Karbala for Arbaeen were killed and 17 others wounded in two bomb attacks, in Baghdad and in Iraq's eastern province of Diyala, Xinhua reported.

The pilgrimage, a religious observation that falls after 40 days of mourning for Imam Hussein, a grandson of the Prophet Muhammad killed in a 7th century battle, was banned under Saddam Hussein. It is expected to draw as many as 10 million people to the city of Karbala over a period of 10 days, and has been an annual flash point for sectarian violence. 

Separately, a suicide car bomb attack Thursday at a central Iraqi police headquarters in the volatile Diyala Province killed two police officers and a female journalist, according to reports.

It was the third suicide attack on local forces in as many days, raising fears of an renewed insurgent campaign targeting Iraqi security forces and government officials.

Sunni insurgents and Shiite militia have stepped up attacks in recent months on Iraqi policemen and soldiers, seeking to undermine faith in the security forces before a full U.S. military withdrawal by the end of this year.

In another attack in Diyala on Wednesday, a suicide bomber driving an ambulance reportedly killed up to 15 people and wounded more than 50 at a police training center.

And on Tuesday, at least 49 people were killed in former dictator Saddam Hussein's hometown of Tikrit when a suicide bomber attacked a line of police recruits.

That was the bloodiest attack in Iraq since Prime Minister Nuri al-Maliki won support in December for his reappointment, ending nine moths of political stalemate following the election.

Overall violence has fallen sharply since the 2006-07 peak of sectarian violence between the once-dominant Sunnis and majority Shiites triggered after the 2003 U.S.-led invasion.

But Sunni Islamist groups like Al Qaeda still battle Iraqi security forces, particularly in ethnically mixed Diyala, Baghdad and the turbulent northern province of Nineveh.

In one attack Thursday, the suicide bomber rammed a minibus loaded with explosives into the main gate at Diyala police headquarters in central Baquba. The headquarters was preparing an exhibition of weapons and ammunition confiscated by Iraqi security forces from insurgents in 2010.