The incident is the first killing of a candidate ahead of Iraq's parliamentary elections, scheduled for November 11.

"A bomb exploded under the vehicle of Safaa al-Mashhadani, a current member of the Baghdad Provincial Council and a candidate for parliament. He died instantly and three of his bodyguards were seriously wounded," the source, who requested anonymity as they were not allowed to brief the media, told AFP.

The source explained that "the incident occurred at dawn on Wednesday in Tarmiyah", located 40 kilometres north of the capital and part of the Baghdad province.

Mashhadani was running with one of the largest Sunni Muslim coalitions, led by businessman Khamis al-Khanjar and parliament speaker Mahmoud al-Mashhadani.

The upcoming elections are the sixth since the 2003 United States invasion of Iraq, which toppled longtime ruler Saddam Hussein.

The majority of Iraq's 329 lawmakers represent Shiite parties aligned with neighbouring Iran.