BAGHDAD, (Reuters) – Twin car bombs killed at least 40 people and wounded 145 others on Friday in Iraq’s holy city of Kerbala as hundreds of thousands of Shi’ite pilgrims observed a major religious rite, health officials said.

The attack on the final and most important day of the Arbain festival was the third major strike this week against Shi’ite pilgrims amid a political furore over the banning of candidates, many of them Sunnis, from a March 7 election.

“We were walking back home in groups after we finished our rites and all of a sudden a huge explosion happened. I saw the balls of fire and smoke rise from the scene ahead,” said pilgrim Muhammad Nasir, 31, a day labourer being treated at a hospital. “People were running away. Security forces cordoned the scene off. There were pieces of flesh scattered around.”

A senior health official in Kerbala, who spoke on the condition of anonymity, said that 40 bodies had been brought in to the main hospital. Other sources put the death toll at 31.

Mehdi al-Fatlawi, a medic at the city’s al-Hussein hospital, said: “Bodies in plastic bags, some beyond recognition, and many others wounded. The hospital wards were full of wounded.”

Police said the bombings occurred to the east of the city, which lies 80 km (50 miles) south of Baghdad. Details were sketchy as most officials were observing Arbain, which marks the end of 40 days of mourning for Imam Hussein, a grandson of the Prophet Mohammad, who died in a 7th century battle at Kerbala.

Overall violence in Iraq has fallen, but Shi’ite gatherings remain a target for Sunni Islamist insurgents. Militants have also made a series of suicide assaults on Baghdad since August aimed at undermining Shi’ite Prime Minister Nuri al-Maliki.

Banned under Saddam Hussein, Arbain and other Shi’ite religious events have drawn millions of Shi’ites, not just from Iraq but also from nearby countries like Iran since the Sunni dictator was ousted in the 2003 U.S. invasion.

A bomb planted on a cart pulled by a motorbike killed at least 20 pilgrims on Wednesday as they streamed into Kerbala.

More than 40 were killed outside the capital on Monday as they began the long walk to Kerbala.

The attacks added to sectarian tensions that have been rising as a result of an election ban imposed on almost 500 candidates suspected of links to Saddam’s outlawed Baath party.

Although the list contained more Shi’ite than Sunni names, many Sunnis believed it was aimed at denying them a fair share of power in the election. Sunnis boycotted elections in 2005 and their anger at their loss of power helped fuel the insurgency.

An appeals panel announced on Wednesday that the ban would be suspended, allowing the barred candidates to stand for election but subjecting them to review after the vote.

Angered by the panel’s action, the Shi’ite-led government called a special session of parliament for Sunday and asked the high court to rule on the decision’s legality.

Iraq’s Shi’ite majority and minority Kurds were often brutally oppressed by the Baath party under Saddam and many of its current Shi’ite leaders were forced to spend years in exile.

Pilgrims in Kerbala said they were fearful of the arduous journey home after the rite finishes on Friday, despite the deployment of tens of thousands of troops and police. “I have concerns and expect to be targeted on the return route,” said Balasim Khalaf, 51, a resident of Balad, 80 km (50 miles) north of Baghdad. “This is our destiny but it won’t stop us from conducting our rituals.”

Some pilgrims said they had decided not to risk the trip home on Friday while others seemed paralysed with fear. “The visit has become a hell for us. We don’t know what to do, whether to stay or return,” said Aqeel al-Magsosi, 32, who was in Kerbala with his wife and two children.