At least seven people were killed in a suicide car bomb attack in a northern Iraqi town that has seen deadly clashes between Kurdish and Shia paramilitary forces, the mayor and security sources said on Saturday.
There was no immediate claim of responsibility for the blast in Tuz Khurmatu, about 175 km (110 miles) north of Baghdad.
The target was a police checkpoint near the entrance to a market in a predominantly Shi'ite Turkmen district, mayor Shalal Abdul said.
Four of those killed were police, and at least 17 others were wounded, local police said.
Efforts to push back Islamic State militants in northern and western Iraq have been complicated by sectarian and ethnic rivalries. These include a contest for territory which is claimed by the Shi'ite-led government in Baghdad, but which the Kurds want as part of their autonomous region in the north of the country.
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 air strikes.
The tensions risk further fragmenting Iraq, a major OPEC oil exporter, as it struggles to contain Islamic State. The group poses the biggest security threat since a U.S.-led invasion toppled autocrat Saddam Hussein in 2003.
Two weeks ago, clashes between the militias left at least 16 people dead and cut a strategic road linking Baghdad to the northern oil city of Kirkuk.