At least 40 people were killed when a bomber detonated his explosive vest at a Shiite Muslim funeral hall in the eastern province of Diyala, security and medical sources said on Monday.
DAESH terrorist group claimed responsibility for the suicide attack, according to a statement posted on the SITE monitoring group's Twitter account.
A further 58 people were wounded in the attack at a funeral for a relative of a Shiite militiaman in Muqdadiya 80 km northeast of the capital Baghdad.
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. DAESH claimed responsibility for that attack as well.
Security officials and police in Diyala said the target of the attack was two local commanders of the Hashid Shaabi umbrella group of Shiite militias who were attending the funeral ceremony for one of their relatives.
"The suicide attacker approached the local Hashid commanders and then blew his vest up, killing both with many others," said one police major on condition of anonymity.
Hashid Shaabi, backed by Iran, has been fighting alongside the Iraqi Army against DAESH.
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 DAESH.