A roadside bomb struck a minibus packed with pilgrims bound for the holy Shi'ite city of Kerbala on Friday even as Iraqi authorities deployed over 40,000 police and soldiers to avert new violence in the annual rite.

Police said one pilgrim was killed and nine were wounded in eastern Baghdad in the attack, which came as thousands make their way, some walking for days, to Kerbala to mark the birth of Imam al-Mehdi, a revered figure in Shi'ite Islam.

Near the town of Iskandariya, bloody mattresses and a heap of shoes lay by the roadside where 19 people were killed and 75 wounded overnight by a female suicide bomber, who detonated an explosive vest among pilgrims stopped for their evening meal.

Pilgrims had piled nearby the black abayas belonging to women who were slain.

Iraqi security forces, backed by helicopters and hundreds of snipers perched on rooftops, say they will search pilgrims and use bomb-sniffing dogs to ferret out explosives as part of an effort to avoid the bloodshed that continues to mar such religious events even as overall violence in Iraq drops sharply.

"We have set up scores of watch towers, and have cameras placed in open areas, crossroads and major entrances," said Kerbala police chief Major-General Raad Shakir.

The pilgrimage is one of several annual events that have become shows of force for Iraq's Shi'ite majority since the fall of Sunni Arab leader Saddam Hussein, who restricted Shi'ite religious practice. Sunni Arab militants often strike them.

Suicide attacks in Baghdad and Kerbala during a 2004 pilgrimage killed 171 people. In the war's deadliest incident, more than 1,000 pilgrims were killed in 2005 during a stampede on a bridge triggered by a rumor of a bomber in their midst.-Reuters