Baghdad: Iraq’s oil ministry sharply criticised the autonomous Kurdish region on Friday for its move to sell oil independently, saying it was a violation of the constitution and amounts to smuggling.

The strongly-worded statement came after Kurdish authorities announced that its first shipment of crude oil exported directly to Turkey had gone on sale, with more expected to follow.

It is just the latest chapter in a long-running tussle between the federal government and the Kurdistan region over natural resources.

The three-province region’s plan to sell oil it has exported to Turkey “is considered ... an explicit violation of the requisites of the Iraqi constitution,” the oil ministry said in an English-language statement.

The federal State Oil Marketing Organisation “is the exclusive, sole official body authorised to enter into contracts for the export of hydrocarbon resources, including crude oil and gas,” it said.

Any other exports are “considered as ‘smuggled crude’ and in violation of the valid laws,” it said, also criticising Ankara for facilitating the move by Kurdistan.

The Kurdish region earlier this week issued a statement giving “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 on the region’s website 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.