Clashes have been reported between Iraqi and Kurdish forces in the city of Kirkuk and around the nearby oil fields.
Iraqi state television say Iraqi troops had taken control of some areas in the northern Kirkuk province recaptured by Kurdish forces from the Islamic State in 2014 “without fighting”, but this has been denied by Kurdish officials.
An exchange of artillery fire could be heard south of Kirkuk city, with the conflict a nightmare scenario for the US, which has armed and relied upon both sides in its fight against IS.
Tensions have intensified between the Arab-led Baghdad government and the autonomous Kurdistan region after those living in the northern province voted overwhelmingly for independence in a vote last month. The outcome of the referendum has not been recognised by the international community, with the US and others pushing for the two sides to reach a diplomatic solution that does not further destabilise the region.
Iraqi Prime Minister Haider al-Abadi has denied the legitimacy of the referendum and demanded Kurdish authorities to annul the result, but the Kurdish authorities have called for dialogue over the issue of an independent Kurdish state.
Last week, Abadi said he would accept a “joint administration” of the Kurdish region and he did not want an armed confrontation between the previous allies.