President Donald Trump tweeted about the incident, saying: "Five Most Wanted leaders of ISIS just captured!".
Ismail al-Eithawi, who also uses the alias Abu Zaid al-Iraqi, was captured in February in Turkey by Turkish authorities and handed over to Iraqi agents, Iraqi security advisor Hisham al-Hashimi told Reuters on Thursday.
Iraq has opened polling stations for security forces as well as expatriates in the first national elections since the Arab state declared victory over the Takfiri Daesh terror group.
IS fighters no longer control significant pockets of territory inside Iraq, but do maintain a grip inside Syria along Iraq's border. Those held include Saddam Jamal, a Syrian who served as the group's governor of Syria's eastern Euphrates region.
"Only that captured the five most wanted leaders of ISIS", he said on Twitter, without specifying details.More news: Pakatan Harapan wins Malayasia elections, Mahathir to be new PM
Iraqis security forces, expats start voting in parliamentary elections. They were shown in yellow prisoner uniforms.
Apart from Eithawi and Jamal, the operation captured three field commanders: Syrian Mohamed al-Qadeer and two Iraqis, Omar al-Karbouli and Essam al-Zawbai, Hashimi said.
The joint Iraqi-American intelligence team then persuaded Ithawi to contact several of his ISIS colleagues who had been hiding in Syria and lure them across the border, the officials said.
Incumbent Prime Minister Haider al-Abadi has cautiously trodden a diplomatic middle course between Tehran and Washington, ensuring the cooperation of both in the war against IS, which overran a third of Iraq in 2014.