Iraqi authorities say Kurdish forces have taken over 2 oil fields near northern city of Kirkuk

Iraq's Oil Ministry says Kurdish fighters have taken over two oil fields outside the disputed northern city of Kirkuk.

Ministry spokesman Assem Jihad says the Kurdish forces known as peshmerga seized the Bai Hassan and Kirkuk oil fields before dawn on Friday. He says the move is "a violation to the constitution ... and a threat to national unity."

There was no immediate comment from authorities in the Kurdish self-rule region of northern Iraq.

The already difficult relationship between the Kurds and Iraq's central government has sharply deteriorated in recent days.

On Wednesday, Prime Minister Nouri al-Maliki accused the Kurds of harboring the Sunni militants who have overrun much of the country. The Kurds responded by declaring their politicians will boycott Cabinet meetings and renewing demands that al-Maliki step down.