24 people were killed when a bomber detonated his explosive vest at a funeral for a Shiite Muslim militia terrorist in the eastern province of Diyala, security and medical sources said on Monday.
A further 55 people were wounded in the attack.
There was no immediate claim of responsibility for the attack in Muqdadiya, 50 miles northeast of the capital.
It followed a twin suicide bombing in Baghdad’s Shiite district of Sadr City on Sunday which left 78 people dead and more than 100 others wounded.
Islamic State terrorists claimed responsibility for that attack and an earlier offensive on army and police positions in the western suburb of Abu Ghraib that killed 17 security forces.
Iraqi officials declared victory over the terrorists in Diyala a year ago, but Islamic State has remained active. The Badr Organisation has established itself as the ascendant militia in the region after rolling back the terrorists.
Militia elements have been accused of attacking Sunni mosques and residents in Diyala following similar bombings in January, but the groups have denied the allegations and blamed Islamic State.