Iraq's autonomous Kurdish region has exported $2.87 billion of oil by pipeline and truck since the beginning of 2014, it announced in a statement on Friday.

The three-province northern region's independent export of crude has been a long-standing point of contention with the federal government in Baghdad, which considers it illegal.

"Since January 2014 to date, 34.5 million barrels (mmbbls) of oil have been exported from the Kurdistan Region, of which 21.5 mmbbls were sold through Ceyhan" in southern Turkey, the statement from the region's ministry of natural resources said. "The balance was trucked to Mersin in Turkey.

"The total value of the exported oil in cash or kind is $2.87 billion," it said.

The ministry said it is treating the proceeds as part of the 17 percent of the federal budget to which the region is entitled, "which has been suspended by the federal government since January 2014".

Baghdad and Iraqi Kurdistan are at odds over various issues, including natural resources, power-sharing and control of a swathe of disputed northern territory.

But these issues have been overshadowed in recent months as both federal and Kurdish forces battle the Islamic State jihadist group, which has seized significant parts of the country.