Rubble in the streets of central Kirkuk, Iraq.

Three roadside bombs exploded here on Sunday, near a Shi'ite mosque.

A car bomb and a roadside bomb were detonated elsewhere near a Kirkuk television station.

And bombs planted in a car in the city of Jalawla killed two Kurdish military recruits just hours earlier.

The blasts killed at least nine people and injured 30.

The carnage comes at a time of escalating tension between Baghdad and the autonomous Kurdistan region in the north

Friction is growing after both regions sent troops to reinforce positions along the contested internal frontier.

Although Kirkuk sits outside the three northern provinces administered by Kurdistan, ethnic Kurds lay historical claim to the city and say it should be part of the Kurdish region.

Kurdistan has run its own government and armed forces since 1991.

But the Kurdish region has increasingly clashed with Baghdad by signing oil agreements with companies like Exxon Mobil-- deals the central government dismisses as illegal.