The death toll from a suicide bombing in Iraq's Shiite holy city of Karbala on Monday rose to 43, with 55 others wounded, an interior ministry source said.(Xinhua/Reuters Photo)

The witness, who did not identify himself, told AP Television News that a woman in the crowd had blown herself up.

If true, it would be among the deadliest attacks carried out by women during the Iraq conflict.

Female suicide bombers have been involved in at least 20 attacks or attempted attacks since the war began, including the grisly bombings of two pet markets in Baghdad that killed nearly 100 people last month.

The US military has warned that insurgents are using female attackers because they can more easily avoid checkpoint searches and can hide the explosives under traditional all-encompassing black Islamic robes.