Arbil: Iraqi Kurdish leaders plan to hold a referendum on the region’s independence by November, an official said on Wednesday, in a move that could lead to the break-up of Opec’s second-biggest oil producer.

Masoud Barzani, president of the semi-autonomous Kurdish Regional Government, wants the vote to take place before the US presidential election, said Kifah Mahmoud, an adviser at the president’s office. He didn’t explain the reasoning behind the timeline.

Barzani met Kurdish political leaders on Tuesday to discuss the timeline, Mahmoud said. While they all agreed to hold the referendum, the vote “doesn’t mean independence. It is the decision of the people,” he said.

The Kurds, who historically have resisted control by Arab-dominated governments in Baghdad, are independently developing oil reserves they say may total 45 billion barrels — equivalent to almost a third of the deposits in the rest of Iraq, according to BP Plc data.

Saad Al Hadithi, a spokesman for Iraqi Prime Minister Haider Al Abadi, said “any unilateral position from any party without coordination or approval will be against the constitution and illegal”.

The Kurds have been holding back crude produced in their enclave in northern Iraq and exporting it independently since June via a pipeline through Turkey, as they exercise greater control of their own affairs. KRG finances have been eroded by a budget impasse with Baghdad, the collapse in crude prices, and the cost of a war against Daesh militants.