Iraq's Kurds have seized two oilfields, according to Iraq's oil ministry, as tensions between the autonomous region and Baghdad become increasingly strained.
Kurdish peshmerga forces have taken over oil production facilities at Bai Hassan and oilfields in Kirkuk, the ministry said in a statement.
The two sites have a combined output capacity of around 400,000 barrels a day, the ministry added.
Kurdish lawmakers have said they would boycott central government meetings after Iraqi Prime Minister Nouri al-Maliki accused the Kurds of harbouring terrorists from the Islamic State, formerly known as Isis (Islamic State of Iraq and the Levant).
Kurdish forces have asserted authority in some areas of northern Iraq since central government fled the region in the face of an Isis-led assault on Mosul and surrounding regions in June.
The Kurdistan Regional Government (KRG) leadership has since called on the Kurdish parliament to prepare for a vote on independence, in a move that has infuriated Baghdad.
Iraq's central oil ministry condemned the Kurds' recent manoeuvres, saying the KRG should "support security forces in confronting terrorist groups rather than using the conditions to raid and occupy oil fields".
Iraq's foreign minister Hoshiyar Zebari said Kurdish MPs had halted daily business with the central government and warned that the country faced the prospect of breaking up if a national government was not formed soon.
"The country is now divided literally into three states - Kurdish, a black state [Isis] and Baghdad."
Caretaker PM Maliki has struggled to form a government since elections were held in April. The situation has been complicated further by the Islamist insurgency in the north of the country.