ree car bombs including a suicide attack, killed at least four people and injured dozens others in disputed territory in northern Iraq on Sunday.

Three car bombs including a suicide attack, killed at least four people and injured dozens others in disputed territory in northern Iraq on Sunday.

The unresolved row over the swathe of land, which Iraqi Kurdistan wants to incorporate into it's three-province autonomous region over Baghdad's objections, is cited by diplomats as among the biggest threats to Iraq's long-term stability.

In the town of Riyadh, just west of the ethnically-mixed city of Kirkuk, three policemen were killed and 14 people were wounded when a suicide attacker set off a minibus rigged with explosives outside the town's police headquarters, according to police Brigadier General Sarhad Qader.

Among the wounded in the 10:00 am (0700 GMT) attack were nine policemen, including local police chief Major Mundher Ahmed.

Another person was killed and 27 were wounded by two car bombs targeting Shiite Turkmen areas of Tuz Khurmatu, another ethnically-diverse town in the disputed territory, which stretches from Iraq's eastern border with Iran to its western frontier with Syria.

The row is one of several between the central government and the autonomous Kurdish region, and diplomats and analysts often voice worry that tensions tied to the disputes could spill over into armed conflict.