KARBALA (AFP) - A suicide attacker driving a minibus on Wednesday killed 20 Shia pilgrims, including women and children, travelling on foot to a shrine city in central Iraq, health and security officials said. The bomber struck a crowd of pilgrims on the outskirts of Karbala, 110 kilometres south of Baghdad, in an attack that also left 117 people wounded. The pilgrims had been travelling on foot from Hilla in Babil province to Karbala to observe Fridays Arbaeen rituals. A senior provincial health official who gave the toll said at least one woman and three children were among the dead. An interior ministry official, who confirmed the casualty toll, said the bomber detonated an explosives-laden bus. Arbaeen marks 40 days after the Ashura anniversary commemorating the sacrifice of Hazrat Imam Hussein (RA) in 680 AD. Tens of thousands of Shias, including many from neighbouring Iran, make their way annually at Arbaeen to pay homage at Imam Husseins shrine in Karbala. In Baghdad on Monday a female suicide bomber blew herself up among a crowd of pilgrims who were making their way to Karbala for the rituals, killing at least 41 people.