Four female suicide bombers and a gunmen killed at least 68 people and wounded almost 300 others in a string of attacks in central Baghdad and Kirkuk on Monday, authorities said.

In Baghdad, three suicide bombers detonated their explosives in three locations within 30 minutes of each other, killing at least 30 people and wounding 83 others, an Interior Ministry official said as cited by CNN.

Most of the victims were Shiite pilgrims taking part in an annual march to one of the Shiites' holiest shrines.

In a separate attack, a bomb killed at least 15 people and wounded 170 others at a Kurdish rally in the northern city of Kirkuk, Iraqi officials said.

On Sunday, at least seven pilgrims were killed south of Baghdad in an ambush by a gunman.

The Shiite pilgrims were commemorating the death in A.D. 799 of Musa al-Kadhim, one of the 12 principal Shiite imams.

Pilgrims have been warned against accepting food and drinks from strangers. They've also been told to discount rumours of suicide bombers as such a rumor triggered a stampede that killed about 1,000 people during the pilgrimage in 2005.

The use of female bombers is an increasingly common method for staging suicide attacks in Iraq because male security forces will not search women and few women have been trained to conduct searches.