A woman suicide bomber killed as many as 54 Shia pilgrims marching through Baghdad to the holy city of Karbala in the south today, in the latest explosion to shake the capital in the run-up to next month’s elections.

The woman was dressed in the traditional black cover-all cloak, or abaya, worn by devout Shia women, and which police said allowed her to hide a large explosive device and mingle with pilgrims marching through the city towards Karbala.

The pilgrims were travelling to take part in the festival of Arbayeen, which marks the anniversary of the death of Imam Hussein, the grandson of the Prophet Mohammed, in 680 AD.

The bomber blew herself up in a rest stop tent where pilgrims had gathered for refreshments. 

Witnesses said that a huge fireball ripped through a crowd, leaving bodies strewn on the ground, their banners drenched in blood and their sandals scattered across the road.

More than 100 people were wounded in the blast in the mainly Shia district of Shaab in northern Baghdad, which a few years ago was a favoured dumping ground for bodies of Sunnis killed by Shia death squads.

The wounded were rushed to hospital in cars and ambulances as locals rushed to help.