BAGHDAD, Iraq - Five blasts in Iraq, including at least four suicide bombings, killed at least 12 people Saturday as Shiite Muslim worshippers around the country celebrated the holiest day of the year. The attacks came one day after a string of bombings killed at least 36 people.

Saturday's attacks, during the religious festival of Ashoura, came despite stepped-up security around the country. Authorities had hoped to prevent a repeat of last year's attacks during Ashoura, in which insurgents killed at least 181 people in twin blasts in Karbala and Baghdad.

At least four blasts were suicide bombings, while the fifth occurred inside a public bus in Baghdad, killing at least one child and five adults. The bus was stopped in the northern Kadhimiya neighborhood, which is predominantly Shiite, but there were no further details on the explosion or casualties.

On Saturday, a suicide bomber walked into a tent outside a Sunni mosque in western Baghdad and blew himself up, killing at least three people and injuring 10, police captain Hussain al-Ani said. About 50 people were inside the tent attending a funeral.

It was unclear why the attacker blew himself up inside a tent full of Sunnis, set up outside the Fatah Pasha mosque, but similar structures were set up outside Shiite mosques for the Ashoura celebration. Most attacks by insurgents - who are thought to be predominantly Sunni extremists - are aimed at Shiites.

Another suicide bomber who tried to kill a group Iraqi National Guard troops near a mosque in northwest Baghdad on Saturday detonated prematurely and killed only himself.

A third bomber blew up a car outside an Iraqi National Guard base in Baqouba, 35 miles northeast of Baghdad, killing one Iraqi guardsman and wounding another, police Col. Muthafar Shahab said. The suicide bomber also died in the blast, he said.

A fourth suicide bomber blew up his car at an Iraqi army checkpoint in Latifiya, 20 miles south of the capital, killing two Iraqi soldiers, an army officer said on condition of anonymity.

Gunmen also holed up in a building and opened fire on a funeral procession in Baghdad in which mourners were carrying coffins of some of the dead killed Friday in a bombing at the capital's al-Khadimain mosque, witnesses said.

Iraqi National Guard troops guarding the procession foiled that attack, returning fire and capturing one of the assailants, said Sgt. Ali Hussein. No casualties were reported.

Authorities, bracing for violence Saturday, stepped up security around the country. In Karbala, vehicle traffic - even motorcycles, bikes and pushcarts - was prohibited in an attempt to avert bomb attacks.

Insurgents staged five attacks on Friday leaving at least 36 people dead, and Shiites blamed radical Sunni Muslim insurgents, who have staged car bombs, shootings and kidnappings to try to destabilize Iraq's new government.

"Those infidel Wahhabis, those Osama bin Laden followers, they did this because they hate Shiites," said Sari Abdullah, a worshipper at Baghdad's al-Khadimain mosque who was injured by shrapnel from the explosion Friday. "They are afraid of us. They are not Muslims. They are infidels."

A militant Web site posted claims of responsibility from the al-Qaida affiliate in Iraq for the Baqouba bombing and an attack on a police checkpoint in Baghdad. There was no way to verify the claims.

Mouwaffaq al-Rubaie, the national security adviser for the interim government, accused Jordanian-born terror suspect Abu Musab al-Zarqawi and former Baath party members of trying to provoke a sectarian civil war.

"It's a paradoxical idea when they claim that they are fighting the infidels and at the same time, they kill Muslims during Friday prayers," he said.

In a reminder of the dangers facing American troops here, a U.S. soldier was killed Friday on patrol in northern Iraq and a second was killed in the south, the military said. Three other American soldiers were killed in separate attacks in the country's north on Wednesday and Thursday.