Kurdish peshmerga forces took control of production facilities at two northern Iraqi oilfields on Friday, replacing Arab workers with Kurdish personnel, Reuters reported.
The national oil ministry in Baghdad condemned the takeover at the Kirkuk and Bai Hassan fields and called on the Kurds to withdraw immediately to avoid "dire consequences".
The move came a month after Kurdish forces took control of the nearby city of Kirkuk, following the withdrawal of Iraqi armed forces in the face of a lightning assault by Islamic State militants, who have seized large parts of north and west Iraq.
The violence has also escalated political tension between Prime Minister Nuri al-Maliki and Kurdish leaders, who have pulled out of Maliki's Shi'ite-led government.
"The ministry of oil confirms that peshmerga armed forces together with some civilians entered crude oil production stations in the fields of Kirkuk and Bai Hassan early this morning and expelled workers," a ministry spokesman said."The ministry warns the Kurdistan region strongly about the danger of such irresponsible behaviour which is considered a violation of the constitution and national wealth."
"...We appeal to rational Kurds about the need to understand the danger of such attitude and to ask the people responsible for this disorderly behaviour to withdraw immediately from these sites in order to avoid dire consequences," the spokesman said.