KERBALA, (Reuters) – 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 rumour of a bomber in their midst.

During the last big Shi’ite pilgrimage in Baghdad last month three female suicide bombers killed nearly 30 worshippers.

Suicide bombings by women have become far more common this year in Iraq, where U.S. forces blame Sunni al Qaeda militants for deploying female bombers to evade security searches.

Shakir said around 2,000 female police officers would be searching women making the annual Sha’abaniya pilgrimage.

In Kerbala, police in fatigues and red berets checked ID cards and patted down faithful entering the golden-domed Imam Hussein mosque, strung with brightly coloured neon lights.

Outside the mosque, throngs of pilgrims, some of them women barely visible under their black robes, sat on blankets.

Authorities have banned people from carrying weapons and chanting sectarian slogans. On the roads to Kerbala, police watched over pilgrims carrying belongings on their backs in the scorching summer heat.

Despite the precautions, Kerbala is bracing for the worst. Local health director Alaa Hammoudi said that 40 medic units were standing by, and that extra hospital beds were made ready.

Near the mosque, makeshift clinics were set up in tents and trailers. Some pilgrims donated blood.

Shi’ites believed that Mehdi, the 12th imam, disappeared in the ninth century but never died. They believe his return will signal the advent of peace and justice on earth.

Last year’s pilgrimage for the Mehdi’s birth saw gunbattles in Kerbala between Shi’ite factions, which led to a ceasefire by anti-American cleric Moqtada al-Sadr that U.S. forces say is one of the factors contributing to Iraq’s fall in violence.

A spokesman for the U.S. military said that U.S. forces would support Iraqi troops if needed.

The United States has been seeking to highlight its secondary role in such security operations as U.S. and Iraqi officials negotiate an agreement to outline the U.S. presence in Iraq after a U.N. mandate expires at the end of the year.

Iraq’s Shi’ite-led government is hoping that U.S. forces will halt patrols of Iraqi cities and towns by the middle of 2009, and withdraw combat troops by 2010 or 2011. So far, President George W. Bush has resisted a firm timetable, but has spoken of a “time horizon” for a gradual drawdown of troops.

The U.S. military announced on Friday the death of a marine killed by small arms fire in western Iraq, the 15th U.S. service member to die in Iraq this month. Just 13 died in all of July, the least deadly month since the war began.