Three suicide bombers struck at Kurdish security forces and the local headquarters of a Kurdish political party in the disputed area of Iraq on Wednesday, May 8, killing three people, police and medics said, according to Reuters.

Tensions between Iraq's Sunni, Shi'ite and ethnic Kurdish communities have increased since the withdrawal of U.S. troops in December 2011.

Wednesday's attacks took place in a band of oil-rich territory over which both the central government in Baghdad and the Kurds, who run their own administration in the north, claim jurisdiction.

At the heart of the dispute is the ethnically mixed city of Kirkuk, 250 km (155 miles) north of Baghdad.

A suicide bomber in a car targeted the offices of the Patriotic Union of Kurdistan (PUK) in Kirkuk on Wednesday, killing one guard, police and hospital sources said.

Another bomber in Kirkuk targeted Kurdish security forces known as peshmerga, killing one, police and medics said. In the town of Tuz Khurmato, about 67 km south of Kirkuk, a suicide bomber in a car killed one peshmerga, security sources said.

No group immediately claimed responsibility for the attacks. Iraq is home to a number of Sunni Islamist insurgent groups.

The Iraqi army and peshmerga forces reinforced positions along their contested internal boundary last year, raising the temperature in a long-running feud over land and oil rights.

More Kurdish troops deployed beyond the formal boundary of their autonomous region last month, a move they said was to protect civilians after clashes broke out between Sunni protesters and Iraqi security forces in the town of Hawija, near Kirkuk.