BAGHDAD; Ten people were killed, including a woman and six policemen, in violence across Iraq on Wednesday, Iraqi police said.

In the deadliest attack, a roadside bomb exploded as policemen were travelling by car through a market in the southern Baghdad neighbourhood of Dora, killing five of them, police said.

A further eight people were wounded, including three policemen, in a midnight blast in the predominantly Sunni district, a police official told AFP, requesting anonymity because he is not authorised to speak to the media.

In the restive city of Mosul, 370 kilometres (230 miles) north of Baghdad, one policeman was killed when three gunmen in a car opened fire on a police checkpoint in the north of the city and then fled the scene.

The shooters then moved on to a second checkpoint in the area, which had been informed of the violence nearby, and entered a gun battle with police there.

Two of the three gunmen were killed in the clashes, while a third was injured and arrested by police.

A man who worked at a pharmaceutical factory in Mosul was killed and two other people injured after a "sticky bomb" attached to their car exploded on a road 10 kilometres north of the town, a local policeman said.

A car bomb Wednesday morning in Ramadi, 100 kilometres west of the capital, killed a woman and wounded four other people, including two policemen, a local police official said.

The explosion, near a mosque in the centre of the city, also destroyed two cars.

Ramadi is the capital of the western province of Anbar, a one-time bastion of the Sunni insurgency that has seen a sharp drop-off in violence over the past 18 months as local tribes allied with US-led forces.

But attacks have in recent weeks begun to spike in Anbar again -- a car bomb in a popular market in Haditha on Sunday killed four women and three children, while a suicide attack on Thursday close to a police station in the town of Al-Qaim near the Syrian border killed three people and wounded 30.

Violence in Iraq as a whole has dropped off markedly in recent months, but attacks against security forces and civilians are common in the capital and Mosul.

The number of violent deaths in Iraq fell by a third from the June figure of to 437 to 275 in July, the first month local forces have been in charge of security in urban areas since the US-led invasion in 2003 that toppled Saddam Hussein.

The figure in May was 155, the lowest of any month since American troops arrived.