Attackers targeted voters in Baghdad, as thousands of people made their way to polling stations to cast advance ballots before Sunday's national election.
At least 17 people were killed in the Thursday blasts, local officials said, noting that two blasts hit voters waiting outside polling stations.
Insurgent groups have said they will use violence to try and disrupt Sunday’s election, which will determine who will take charge of the country as U.S. forces finish withdrawing.
"Terrorists wanted to hamper the elections, thus they started to blow themselves up in the streets," said Deputy Interior Minister Ayden Khalid Qader, who is responsible for election-related security across the country.
Many of the victims were believed to be security personnel — the main group to cast ballots during early voting since they will be working on election day.
The attacks come one day after 30 people died in three separate attacks in Baquba, a mixed Shiite-Sunni city roughly 60 kilometres northeast of Baghdad.
Hundreds of thousands of Iraqis are expected to take part in Thursday's early voting, a one-day session for people who can't get to the polls Sunday, when the rest of the country will vote.
The UN said more than 350,000 polling station staff are being trained to work in the election.
Roughly 19 million of Iraq’s roughly 28 million people are eligible to vote in the election, which will fill the 325 seats in the Council of Representatives. Iraqi expatriates living in 16 countries around the world will also be eligible to vote.
Sunday's elections are only Iraq's second for a full parliamentary term since the 2003 U.S.-led invasion ousted Saddam Hussein, leading to the eventual creation of the Shia-dominated government that is currently in power.