Three farmers were among nine people killed in attacks in Iraq on Thursday, police and doctors said, as the country struggles to curb its worst violence since 2008.

A magnetic "sticky bomb" killed a man and his wife, both farmers, in the Dujail area as they drove to work, while another farmer was shot dead by gunmen near Balad, officials said.

Another four people were wounded when a roadside bomb exploded as police arrived at the scene of the Balad attack. Dujail and Balad are located north of Baghdad.

The deadliest attack, however, was when a roadside bomb killed three young men in the town of Wajihiyah, northeast of Baquba, the capital of Diyala province.

Areas to the north of Baquba have been hit by numerous attacks in recent days, including a bombing on Wednesday that killed three children at a popular swimming area.

Another bomb exploded south of Baghdad on Thursday near an army checkpoint, killing two people and wounding at least five.

And gunmen killed a woman in her home to the west of the north Iraq city of Kirkuk.

The latest unrest brings the number of people killed in attacks in July to more than 430 -- and upwards of 2,690 since the beginning of the year.

Iraq has faced years of attacks by militants, but analysts say widespread discontent among members of its Sunni Arab minority, which the Shiite-led government has failed to address, has fuelled this year's surge in unrest.