Iraqi Kurdistan has begun sending oil produced in its three-province autonomous region out of the country without the express permission of the central government, an official said on Sunday.
The central government in Baghdad, meanwhile, insisted that it reserved the sole right to export oil, which accounts for the lion's share of the country's income and is at the centre of a dispute between the capital and Kurdistan.
"We started exporting limited quantities of crude oil to Turkey a few days ago," Seerwan Abubaqr, an adviser to the Kurdistan government's natural resources ministry, told AFP.
He said the crude was being exported to Turkey so it could be refined into various products before being brought back to Kurdistan.
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"The central government has pushed us to do this."
Kurdish officials say the central government has barred the dispatch of petroleum products to the northern region, but the oil ministry in Baghdad has persistently denied those allegations.
"Nobody has the right to export oil, gas, or oil products to foreign countries," said Faisal Abdullah, spokesman for Hussein al-Shahristani, deputy premier responsible for energy affairs.
"Only the oil ministry of the government in Baghdad has the right to export oil or oil products."
A dispute over oil between Baghdad and the Kurdish government in Arbil has worsened in recent months, with Kurdistan looking to ramp up oil production and export capabilities, and the region has also cut off oil exports to Iraq in a payment row.
Arbil has signed dozens of contracts with foreign oil firms aimed at boosting its oil sector in recent year, but the central government, which says all oil contracts must go through Baghdad and regards any that do not as illegal, has strenuously opposed such deals.