At least 16 people have been killed in a series of apparent sectarian attacks in Iraq, a day after multiple bombings targeted a Shia political rally in the capital Baghdad.

Police found nine bodies, some bullet-riddled, in several Sunni and Shia districts of Baghdad on Saturday, security officials told the Associated Press news agency.

In the Sunni area of al-Amil in western Baghdad, two people were killed after gunmen in a speeding car opened fire on a group of civilians.

Police and medical officials said four people were killed and 11 wounded after a bomb exploded inside a small restaurant, in the Shia district of al-Nasir in the eastern suburbs of the capital.

Several hours after the Baghdad bombing on Friday, a senior Sunni politician was shot dead in the Shia dominated southern city of Basra.

The reprisal killings come one day after bombings targeted a campaign rally for a Shia group, killing at least 37 people.

An al-Qaeda breakaway group, the Islamic State of Iraq and the Levant (ISIL), claimed responsibility for Friday's attack.

ISIL said the bombings were to avenge what it called the killing of Sunnis and their forced removal from their homes by Shia militias.

'New wave' of violence

Security officials warned on Saturday the latest bout of violence could signal the start of a new wave of violence before next weeks' elections.

The United Nations has reported more than 1,400 people were killed in the first two months of this year alone.

In 2013, the death toll in Iraq climbed to its highest levels with the UN reporting 8,868 killings, the highest since the violence between 2006 and 2008.

On Wednesday, more than 9,000 candidates are taking part in parliamentary elections, the fourth such vote since Saddam Hussein's 2003 overthrow.

Parts of the Sunni-dominated Anbar province won't take part in the election due the violence between security forces and Sunni tribal leaders.

AP