Attacks mostly targeting security forces in and around Baghdad and in northern Iraq, one of them a suicide bombing, killed three people on Sunday, the latest in a spike in unrest ahead of elections.

The suicide bomber blew up a car at a military checkpoint in Abu Ghraib, just west of the capital, killing one person and wounding seven, including at least three soldiers, a security official and a medical source said.

And on the capital's northern outskirts, a magnetic "sticky bomb" attached to a car detonated near a checkpoint, killing the vehicle's driver.

Five shootings and bombings in Kirkuk and Mosul, both northern cities, killed one person and wounded six. All of the injured were policemen or soldiers.

The attacks come ahead of provincial elections scheduled for April 20, due to be held in 12 of Iraq's 18 provinces, the country's first polls since a parliamentary vote in March 2010.

But questions have been raised over the credibility of the polls as they have been postponed in two provinces roiled by months of protests, and 11 candidates have been killed, according to an AFP tally.

Although markedly lower than its peak in 2006 and 2007, levels of violence remain high in Iraq -- at least 266 people have been killed in attacks this month, the highest figure since August 2012.