Israel has imported nearly 1 billion dollars’ worth of oil from Iraq’s semi-autonomous Kurdish region in the past few months, the Financial Times reported on Sunday.

According to the report, Israel purchased 19 million barrels of Kurdish oil, worth roughly $1 billion, between May and August of this year. The massive amount meets two-thirds of the Jewish state’s oil needs and may be a way for Jerusalem to covertly support the Kurds’ fight against the Islamic State, the report said.

“That is the equivalent of about 77 per cent of the average Israeli demand, which runs at roughly 240,000 barrels per day. More than a third of all of the northern Iraqi exports, which are shipped from Turkey’s Mediterranean port of Ceyhan, went to Israel over the period,” continued the report. Industry sources said Israel may have stored or exported some of the oil.

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The Kurdistan Regional Government denied selling the oil “directly or indirectly” to Israel, but said that its main concern was funding the battle against IS and preserving the functioning of government.

“We do not care where the oil goes once we have delivered it to the traders,” a senior Kurdish government adviser in Erbil told the Financial Times. “Our priority is getting the cash to fund our peshmerga forces against Daesh [the Arabic term for IS] and to pay civil servants’ salaries.”

The report stressed that Israel aside, the Kurds in Iraq have exported oil to Italy, France and Greece, deepening a dispute between the Kurds and the Iraqi leadership over oil exports.

“Traders and industry analysts have suggested that Israel may be acquiring the Kurdish oil at a discounted price, though officials in the Kurdistan Regional Government deny this. Others have suggested it may be a way for Israel to funnel financial support to the Kurds,” the report speculated.

A report in February 2015 said an Iraqi Kurdish tanker, United Kalvrvta, had docked in Ashkelon with 1 million barrels of crude oil on board.

In the 1960s, Israel sent Mossad advisers to help Kurdish leader Mulla Mustafa Barzani, and to manage the Kurds’ battles against the Iraqi army.