Attacks killed 24 people in Iraq Tuesday, the latest in a wave of deadly violence that has cast a pall over the country's first general election since US troops withdrew.

The bloodshed, a day after 64 people died in a nationwide spate of blasts, raises questions over whether security forces can protect upwards of 20 million people eligible to vote on Wednesday.

Prime Minister Nuri al-Maliki, under fire over the worst protracted surge in violence in years and a laundry list of voter grievances, is bidding for a third term in the first national election since 2010.

The Shiite premier has trumpeted a battle against jihadists he claims are entering Iraq from war-torn neighbour Syria, with support from Gulf Arab states, including Saudi Arabia and Qatar.

But critics say heavy-handed treatment of minority Sunnis by his government has contributed to the unrest.

With Monday's attacks fuelling fears voters may stay at home rather than risk being caught up in bloodshed, twin bombings hit a town northeast of Baghdad, killing 15 more people, and violence elsewhere left nine others dead.

"I can't imagine the militancy is going to sit back and say, 'Yeah, have your election,'" said John Drake, a London-based security analyst at AKE Group.

"They are going to make a strong statement undermining the government, undermining the capability of the security forces, and hopefully deterring voters so that the vote result will be seen as illegitimate... in the eyes of many of the electorate."

But on a street in Baghdad's Karrada neighbourhood, which has been rocked by three suicide bombings in just two weeks, residents told AFP they were set on voting.

Mahir Ayad, reaching into his pocket to take out a poem written for a friend killed in one of those bombings, said it was his duty to vote.

"Tomorrow, we begin to change our reality, to prove that our friend's blood was not wasted," said Ayad, a 55-year-old waiter.

- 'Won't put up with the situation' -

Laith al-Azzawi said he had only left his home in Karrada on essential trips, and that his ears were still ringing from a recent bombing, but that he remained determined to vote.

"We won't put up with this situation after today," said the 40-year-old, who was wounded in the stomach by the same suicide bombing that killed Ayad's friend.

More than 3,000 people have been killed in violence this year, according to an AFP tally.

The unrest is the worst since Iraq was plagued by all-out sectarian fighting in 2006 and 2007 that left tens of thousands dead.

Authorities have announced a week-long public holiday to try to bolster security for the election, and vehicles are barred from Baghdad's streets from Tuesday evening.

No group has claimed responsibility for the latest bloodshed, but Sunni militants have been accused of launching previous attacks to try to derail the political process.

Voters often list an array of grievances, including poor public services, rampant corruption and high unemployment, not to mention the persistent violence, but all that got short shrift as the month-long campaign centred on whether Maliki should get a third term.

The premier contends foreign interference is behind deteriorating security and complains of being saddled with a unity government of groups that snipe at him in public and block his efforts to pass legislation.

The 63-year-old, who hails from Iraq's Shiite Arab majority and is accused by opponents of monopolising power and targeting minority Sunnis, is widely expected to win the largest number of seats in parliament, but is unlikely to win a majority.

In such a case, he would have to win the support of coalition partners, notably Kurdish and Sunni parties as well as fellow Shiites who have been critical of his rule.

With the opposition divided, analysts say Maliki remains the frontrunner.

Forming a government could take months, as rival groups wrangle over the top positions of prime minister, president and parliament speaker.

After previous elections, a de facto agreement has emerged whereby the premier is Shiite, the president a Kurd and the speaker a Sunni Arab.