Iraq's oil exports reached their highest level in decades in December, the oil ministry's spokesman said on Saturday, but vital revenues were being hit by the plummeting prices of crude.

Iraq exported 91.141 million barrels of oil in December for an average of 2.94 million barrels per day, the highest daily average since 1980, Assem Jihad told AFP, citing initial figures.

December exports were far and away the highest in 2014, eclipsing the previous best month by more than 11 million barrels, according to ministry figures.