A wave of attacks across Iraq, including twin car bombs in an ethnically mixed tinderbox city, killed 20 people Wednesday as a year-long surge of violence showed ** signs of let-up. Nearly 50 people were also wounded in the violence, which struck in and around Baghdad, as well as in Salaheddin and Kirkuk provinces to its **rth, all areas afflicted by near-daily bloodshed. 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 auto**mous region over the objections of the central government in Baghdad. ** group immediately claimed responsibility for the attack, but Sunni militants frequently detonate bombs in the disputed territory, capitalising on poor communication between Kurdish and central government security forces.