Two cars have exploded in seperate attacks in southwestern Baghdad's Shia al-Ameen neighbourhood, killing seven people and injuring 21 others, a police source has said, as hospital officials confirmed the casualties.

"A driver parked his car and went to a cigarette stall then he disappeared. Then his car blew up, killing passersby," said the police source said on Saturday.

The second car bomb blew up south of Baghdad in the Shia neighborhood of Zafaraniyah, killing five people and injuring 15 others.

Police sources have confirmed two other car bombs on Saturday. One blew up on al-Sinaa street in central Baghdad killing ten people and injuring 27.

In the Shia neighbourhood of Sadr, another car bomb exploded, killing four people and injuring 12.

Another six people were killed and eight injured when explosives were detonated inside a house in Ramadi, west of the capital.

Authorities also announced on Saturday that a suicide truck bomber targeting a senior police officer's convoy in the town of Baiji killed eight people on Friday, including the ranking official.

Baiji, home to Iraq's largest oil refinery, is located 250km north of Baghdad.

The attack killed police General Faisal Malik, who was inspecting troops in the town, and injured at least 15 people, hospital officials and police officers said.

No one immediately claimed responsibilty for the attack, which comes as US-led air strikes battle the Islamic State of Iraq and the Levant (ISIL), who now control a third of the country.

On Friday, US President Barack Obama authorised the deployment of up to 1,500 more American troops to strengthen Iraqi forces, including in Anbar province, where fighting with ISIL has been fiercest.

The plan could boost the total number of US troops in Iraq to 3,100. There now are about 1,400 US troops in the country, out of the 1,600 previously authorised.