Shi'a Muslims have gathered for an Ashura ceremony at the Imam Abbas shrine in the holy city of Karbala, near Baghdad in Iraq. Ashura is a ten-day event that commemorates the death of the Prophet Mohammad's grandson, Imam Hussein, who was killed in a seventh-century battle. Part of the Shi'a tradition of the event is self-flagellation. Ashura falls on the 10th day of the first month of Muharram (the month of mourning) in the Islamic calendar.

History states Hussein, along with 72 followers, was killed by the soldiers of Caliph Yazid, while fighting injustices. Hussein was then decapitated and his body mutilated, leading to his martyrdom.

As part of the tradition, which is observed in several Islamic nations, devout Shi'a Muslims (including women) re-enact the battle that killed Hussein.

Ashura also highlights the division between Shi'a and Sunni Muslims, and the occasion has in the past been a target of Sunni violence. This year, heightened security measures are in place.

Staff Lieutenant General Othman al-Ghanimi, the Al-Furat al-Awsat operations (which includes Karbala) commander, is believed to have enlisted a 30,000-strong security force to guard the northern, southern and eastern entrances to Karbala. Lieutenant Colonel Ahmed Mohammed al-Hasnawi, the command's spokesman, said forces were also preparing to protect pilgrims on their way back home. According to Karbala's provincial governor, Amal al-Din al-Har, there are approximately two million pilgrims in the city, of whom 200,000 are from abroad.

Below is a selection of photographs of the Shi'a Muslims' Ashura events. Some readers may find the content disturbing.

Also not for the faint-hearted is our review of painful religious traditions from around the world.