Iraqi Kurdistan will export oil via federal pipelines until September 15, an official said on Saturday, extending a one-month confidence-building measure amid a row with the central government in Baghdad.

The northern autonomous three-province region had halted exports for several months on April 1 over $1.5 billion it said was owed to foreign oil companies working in the region that Baghdad had allegedly withheld.

"Kurdistan will continue exporting oil until September 15," an official in the Kurdish natural resources ministry said, speaking on condition of anonymity.

Oil exports were originally resumed on August 7, after a four-month suspension.

The central government and the Kurdish authorities in Arbil are at odds over issues including Kurdistan's refusal to seek approval from Baghdad for oil contracts it has awarded to foreign firms, and over a swathe of disputed territory in northern Iraq.

Baghdad says all oil deals must go through the federal oil ministry, and it regards any that do not as illegal.