Car bombs killed at least 15 people and wounded more than 40 Wednesday on the main streets of two Shiite neighbourhoods of Baghdad, police and medical sources said.

One explosion ripped through a petrol station in the large northern neighbourhood of Sadr City at around 7:00 pm (1600 GMT), as cars were queueing to fill up, witnesses said.

Motorcyclists, who are not allowed to bring their bikes into the station, were also standing in line with empty jerricans.

"I was on my way to having my mobile fixed at the shop when the car exploded on the other side of the street," irrigation ministry employee Ali Dakhel said.

"I heard the sound of the explosion and saw a big fire but when the police began shooting in the air to prevent anyone from coming close, I ran away from the scene," he said.

"There were wounded people shouting and bodies on the ground."

At least nine people were killed, according to hospital and police sources.

Another deadly explosion went off almost simultaneously in the Al-Amin neighbourhood, farther east.

"A car bomb exploded at 6:55 pm on the main street in the Al-Amin area," a police colonel said, giving a toll of six killed.

Hospital sources confirmed the figure. A total of more than 40 people were wounded in the two blasts.

Sadr City has frequently been targeted by Sunni militants carrying out suicide attacks or planting bombs in the capital.

Fears of a surge in attacks during the ongoing Eid al-Fitr feast marking the end of the holy month of Ramadan have led more people than usual to spend the holiday indoors.