Baghdad summoned Turkey's charge d'affaires Sunday over moves by Iraq's Kurdish region to sell oil independently via one of Ankara's ports, saying the move was a violation of its constitution.

Deputy Prime Minister Hussein al-Shahristani, the top official responsible for energy affairs, summoned Efe Ceylan over the announcement by the autonomous Kurdish region last week that its first shipment of crude oil sent directly to Turkey had gone on sale, with more expected to follow.

"Iraq considers the export of oil through its international borders without government approval as a violation," Shahristani said in a statement following the meeting with the Turkish diplomat.

The minister said Turkish officials had prevented representatives from Iraq's oil ministry from overseeing the quantities of oil being delivered and exported from the Kurdish region.

"The Iraqi government holds Turkey legally responsible on this subject, and reserves the right to demand resultant losses," Shahristani said.

Baghdad's summoning of Ceylan is just the latest chapter in a long-running tussle between the federal government and the Kurdistan region over natural resources.

The Kurdish region this week 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.