Iraqi Shiites on Friday sadly witness a major bloodshed for the third time in the past week. A series of attacks targeting Shiite pilgrims killed 43 people and wounded at least 105 others in Iraq's southern shrine city of Karbala when they were observing religious activities.

Two bomb-planted civilian cars parked at two ends of Wadil- Salam bridge, which located east of Karbala, about 80 km south of Baghdad, went off simultaneously just a while after noon, leaving 27 dead and injuring 75 others, an Iraqi interior ministry source told Xinhua.

Just after the blasts, three round of mortar shells hit central Karbala, killing 16 people and wounding 30, according to local officials.

In the same day, another explosion hit eastern Baghdad, killing at least one person and injuring 15 others, said the interior ministry source who declined to give his name.

The attacks occurred as hundreds of thousands of Shiite pilgrims were observing a major religious rite, the culmination activity of the Arbaeen festival.

Arbaeen marks the end of the 40-day mourning after the Day of Ashura, which mourns for Prophet Mohammed's grandson Imam Hussein, one of Shiite Islam's most revered figures, who died in a battle at Karbala in 680 A.D.

This year Arbaeen falls during an already tense period before parliamentary elections. About 5 million Shiite pilgrims from across Iraq and neighboring Iran were pouring into Karbala to pay homage at the Hussein's shrine, which is considered as one of the holiest places of Shiite Islam.

Major Shiite commemorations have been frequently targeted by various armed groups in Iraq, mainly, to incite sectarian violence in the war-torn country.

This year Iraq deployed around 30,000 security police and soldiers to safeguard the ceremonies, and set up check points on main streets leading to Karbala.

Friday's attacks in Karbala were the third major strike against Shiite pilgrims in a week.

On Wednesday, a suicide bomber in a minibus struck crowds of Shiite pilgrims on the eastern entrance of Karbala, killing 20 people and wounding 117 others.

On Monday, a suicide bomber blew up the explosive vest among a crowd of Shiite pilgrims on the outskirts of Baghdad as they began their days-long trip on foot to Karbala, killing 41 people and wounding 106 others.

Some analysts say the attacks were aimed to prove the weakness of the current Shiite-dominated government, while others believe that those behind the attacks want to create a sectarian atmosphere before the upcoming elections.

Officials are monitoring closely for signals that the recent attacks against Shiites could spark retaliations over Sunni targets, fearing it may plunge Iraq back into sectarian violence which tore the country two years ago.

Due to the past several major car bomb blasts, Iraqis have accused the authorities of failing its responsibility to protect them from being attacked by armed groups.

Iraqi security forces are widely depend on a device - a wandlike, handheld mechanism known as ADE-651, to search sealed portions of vehicles for explosives. But there were reports that the British-imported device was flawed.

The U.S. military is rushing delivery of dozens of bomb- detection dogs to Iraq after accusations that ADE-651 mechanical devices are ineffective to pinpoint explosives at checkpoints and other sites.

As the parliamentary elections scheduled on March 7 approaches, U.S. and Iraqi officials have warned an increase of violence in the war-torn country.