Sunni militants who have seized large chunks of Iraq in a recent blitz have started exporting crude from an oil field in the north, a local official said on Friday.

The jihadist Islamic State in Iraq and the Levant (ISIL) began loading 100 tanks with crude late Thursday from the Ujil field, in the northern province of Salah al-Din, local police chief Shalal Abdul said.

“They sell the crude for $12,000 to $14,000 per tank and use the revenues in financing the organisation’s (military) operations.” ISIL — an al-Qaeda splinter group — seized the field, one of Iraq’s largest, in a swift advance into the country’s Sunni heartland in the north and the west last month.

The field, which produces about 20,000 barrels per day, is located outside oil-rich Kirkuk, one of several areas at the centre of a dispute between Baghdad and the autonomous region of Kurdistan.

ISIL exports the crude via Kurdistan to privately owned refineries, Abdul said.

Kurdistan’s president, Massoud Barzani, vowed on Thursday that Kurdish troops — the Peshmerga — will not withdraw from the disputed areas, including Kirkuk, which they took over following the surge by Sunni-led insurgents into Iraq.

Earlier this week, ISIL declared an Islamist caliphate in the territory under its control in Iraq and Syria.

ISIL already controls parts of eastern Syria, raising international fears about the emergence of a regional militant enclave.

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