BAGHDAD (Reuters) - Clashes between Kurdish and Shi'ite Arab paramilitary forces turned a northern Iraqi district into a battlefield on Thursday and cut a strategic road linking Baghdad to the northern oil city of Kirkuk, security sources and local officials said.
The violence in and around Tuz Khurmatu, about 175 km (110 miles) north of the capital, left at least 16 people dead, including five civilians, security and medical sources said.
The Kurdish and Shi'ite fighters have been uncomfortable allies against Islamic State since driving the militants out of towns and villages in the area last year with the support of U.S.-led airstrikes.
The tensions risk further fragmenting the major OPEC oil exporter as it struggles to contain Islamic State, the biggest security threat since a U.S.-led invasion toppled autocrat Saddam Hussein in 2003.
Efforts to push back Islamic State have been complicated by sectarian and ethnic rivalries, including a contest for territory which the Shi'ite-led government in Baghdad claims, but the Kurds want as part of their autonomous region in the north of the country.
Thursday's fighting began in the morning when fighters from the Hashid Shaabi, a government umbrella group comprised mostly of Shi'ite fighters, tried to run a checkpoint south of Tuz Khurmatu manned by Kurdish peshmerga forces, security sources said.
Three Hashid fighters and one peshmerga were killed, they said.
When the dead and several wounded were taken to a hospital in the center of Tuz Khurmatu, Hashid fighters clashed with peshmerga and Kurdish secret police known as Asayish, security and hospital sources said.
Snipers took up positions on residential buildings around the hospital, which was also targeted with mortars, witnesses and security sources said.
As clashes intensified, the peshmerga cut the road leading north from Tuz Khurmatu to Kirkuk, while the Hashid stopped traffic leading south to Baghdad, security sources said.
Civilians closed down their shops and sheltered at home.
"The streets are empty. The city is void of its residents. Gun shots can be heard in several neighborhoods," said Hassan Braim, a member of the Patriotic Union of Kurdistan, one of the main Kurdish political parties.
Violence in and around the hospital left five civilians dead along with three peshmerga and four Hashid members, the security and medical sources said.
The clashes ebbed around sunset but locals said snipers were still in position and the situation remained tense.
Hashid and peshmerga leaders gathered at a local municipal building in a bid to end the conflict, security sources and local officials said.
Reporting By Stephen Kalin; editing by Ralph Boulton