Iraq threatened to boycott Turkish companies and cancel contracts with Turkish firms in an intensifying row over moves to export oil from its northern Kurdish region, in remarks released Saturday.

Oil Minister Abdelkarim al-Luaybi said the planned export of oil from the three-province autonomous region was a "red line" and one that would increase instability in Iraq, arguing that Turkey was not acting in its interests.

Iraqi officials have summoned Turkey's charge d'affaires to Baghdad over the announcement by the Kurdish region this month that its first shipment of crude oil sent directly to Turkey, without passing via pipelines controlled by the central government, had gone on sale, with more expected to follow.

"The Iraqi government will take a series of measures, including boycotting all Turkish companies and cancelling all current (government) contracts with Turkish companies" if Ankara allows oil from Kurdistan to be exported to international markets.

"Turkey must look at this case clearly.... It is not in the interests of Turkey to intervene on this subject.

"This case, for us as Iraqis, is a red line," Luaybi said in remarks released by the oil ministry.

The minister's remarks are just the latest chapter in a long-running tussle between the federal government and the Kurdistan region over natural resources.

The Kurdish region this month gave "public notice of the commencement of the sale of its first shipment of crude oil exported via (the) Kurdistan region's new pipeline through Turkey to the port of Ceyhan."

The sale of the first two million barrels of crude was expected by the end of this month, with more to follow, the statement said.

Kurdistan, which enjoys a high level of autonomy from Baghdad and has its own security forces, government and flag, has also drawn Baghdad's ire for signing contracts with foreign energy firms without its approval.

In addition to disputes over natural resources, the long-standing ambition of Kurdish leaders to incorporate other historically Kurdish-majority areas into their autonomous region, against Baghdad's strong opposition, is another major point of contention.

Diplomats and officials say the disputes are one of the biggest long-term threats to Iraq's stability.