BAGHDAD — Kurdish security forces took over two major oil fields outside the disputed northern city of Kirkuk before dawn Friday and said they would use some of the production for domestic purposes, further widening a split with the central government of Prime Minister Nouri al-Maliki.

The takeover of the Bai Hassan and Kirkuk oil fields were the latest land grabs by Kurds, who have responded to the Sunni militant insurgency that has overrun large parts of Iraq by seizing territory of their own, effectively expanding the Kurdish autonomous zone in the north. Those moves have infuriated al-Maliki’s government while stoking independence sentiment among the Kurds.

Kurdish fighters known as peshmerga pushed into the city of Kirkuk, a major hub for the oil industry in the north, and the surrounding area weeks ago in the early days of the Sunni militant blitz. But until now they had not moved into the oil fields in the area. On Friday, however, the fighters took over the Bai Hassan and Kirkuk fields and expelled local workers, the oil ministry in Baghdad said.

Oil ministry spokesman Assem Jihad denounced the move as “a violation to the constitution” and warned that it poses “a threat to national unity.”

The Kurdish regional government said its forces moved to secure the fields after learning of what it said were orders by officials in the oil ministry to sabotage a pipeline linking oil facilities in the area. It said production would continue, and that staff can return but under Kurdish management.

Production from the fields will be used to fill the shortage of refined products in the domestic market, it said. It also said the Kurdish regional government will claim its “constitutional share” of revenues from the fields to compensate for Baghdad’s cutting off the 17 percent of the state budget – some $20 billion in this year’s projected budget – that is supposed to be given to the Kurdish region.

The central government withheld the funds after the Kurds began moving oil from fields inside the autonomous zone to Turkey independently.

The Kurds have said their earlier moves into disputed lands were intended to protect the areas from Sunni militants after the collapse of the Iraqi military in the face of the insurgency the past month. But the territory they seized has large Kurdish communities and has long been claimed by the autonomy zone.

In past weeks, the president of the Kurdish zone has said the areas won’t be returned – including the highly disputed, flashpoint city of Kirkuk – and he called for Kurdish lawmakers to prepare to hold an independence referendum in the area, a move strongly opposed by Baghdad and the United States. Sunni Arabs and ethnic Turkmens who also claim Kirkuk as theirs have warned of a backlash if Kurds try to monopolize the oil in the region.

A suicide bomber blew himself up Friday at a peshmerga checkpoint outside Kirkuk, killing 13 people and wounding 23, police said.