A wave of attacks across Iraq, including twin car bombs in an ethnically mixed tinderbox city, killed 21 people Wednesday as a year-long surge of violence showed no signs of a let-up.

A wave of attacks across Iraq, including twin car bombs in an ethnically mixed tinderbox city, killed 21 people Wednesday as a year-long surge of violence showed no signs of a let-up.

Nearly 50 people were also wounded in the violence, in and around Baghdad, as well as in Salaheddin and Kirkuk provinces to its north, all afflicted by near-daily bloodshed.

The attacks came a day after a suicide bomber killed a key anti-Qaeda leader battling militants in the conflict-hit province of Anbar.

In Wednesday's deadliest incident, two vehicles rigged with explosives went off in the centre of Kirkuk, killing eight people and wounding nine, said provincial health chief Sabah Mohammad.

Kirkuk, an oil-rich ethnically diverse city, lies at the centre of a swathe of territory that Iraqi Kurdistan wants to incorporate into its three-province autonomous region over the objections of the central government in Baghdad.

Elsewhere in northern Iraq, a suicide truck bomb killed two people in Suleiman Bek, and a corpse booby-trapped with explosives killed a policeman in nearby Tuz Khurmatu.

Both towns, like Kirkuk, lie in the disputed territory, which stretches from Iraq's border with Iran to its frontier with Syria.

In the adjoining province of Salaheddin, two separate bombings left a policeman and a soldier dead.

In the capital, a car bomb killed four people in a shopping area of the neighborhood of Saba Abkar, while separate attacks in different districts left two others dead.

On Baghdad's northern outskirts, two policemen were killed by a roadside bomb.

More than 4,000 have been killed this year, according to an AFP tally.