Four protesters were shot dead on Saturday in clashes between ethnic groups in Kirkuk that broke out after days of tensions. Police and medical sources said all four were Kurdish.

Amir Shwani, a spokesman for Kirkuk police, said in a statement to reporters a curfew had been lifted and vehicles were moving normally in the city on Sunday.

But security forces had deployed additional troops on the streets to “prevent violence and protect civilians”, he said.

The dispute centres on a building in Kirkuk that was once the headquarters for the Kurdistan Democratic Party (KDP) but which the Iraqi army has used a base since 2017.

Military helicopters flew over the city on Sunday, according to four Kirkuk residents who spoke to Reuters by phone.

Shwani confirmed that four protestors had been killed and 15 people were wounded. Residents said police detained several people on Sunday who had participated in the clashes but police refused to comment on any arrests.

Kirkuk, an oil-rich province in northern Iraq along the fault lines between the Kurdish autonomous region and areas controlled by Iraq’s Shi’ite-dominated central government, has been the focus of some of the country’s worst post-Islamic State violence.

Arab residents and minority groups, who say they suffered under Kurdish rule, have protested the KDP’s return to the city.