Two near-simultaneous bombings targeting a Shia religious procession tent south of the Iraqi capital have killed at least eight people and wounded dozens, officials say Al Jazeera reported.
Thursday's violence near Baghdad came during the peak of Ashoura commemoration rituals that mark the death of a key figure in Shia Islam, when Sunni Muslim armed groups typically step up attacks on Iraq's majority community, whom they regard as apostates.
The attacks struck in the town of Hafriyah, in Wasit province, south of Baghdad, on Thursday.
Worshippers were gathering inside a tent where Shias were performing rituals to commemorate the death of Imam Hussein.
Hussein, grandson of the Muslim Prophet Muhammad, was killed by the armies of the caliph Yazid in 680 AD and his death in Karbala has come to symbolise the split between Islam's Sunni and Shia sects.
Security measures have been stepped up in Iraq, with more than 35,000 soldiers and policemen currently deployed to Karbala, about 100km south of Baghdad, and surrounding areas, with security perimeters barring vehicles from entering the city while helicopters hover overhead.
Regional authorities expect two million pilgrims, including 200,000 from outside Iraq, will have visited the city of Karbala in the 10 days leading up to Ashoura, with all of the city's hotels fully booked.
On Wednesday a car bomb targeted a Shia man distributing food in the northern city of Kirkuk, leaving eight wounded.
The violence against Shias is the latest in Iraq's worst unrest since 2008 and forced Prime Minister Nouri al-Maliki to appeal to the US for help in the form of intelligence sharing and the delivery of new weapons systems in an effort to deal with the unrest.
Millions of Shias from Iraq and around the world mark Ashoura, which this year climaxes on Thursday, by setting up procession tents where food is distributed to passers-by and where pilgrims can gather.
Shias make up about 15 percent of Muslims worldwide. They are a majority in Iraq, Iran and Bahrain, and there are large Shia communities in Afghanistan, Lebanon, Pakistan and Saudi Arabia, and Syria.