The Nigerian oil export economy relies mainly on consumers outside North America, the state-controlled Nigerian National Petroleum Corp. said Monday.

"Four regions, namely Europe, South America, Asia and Africa, remain the major destinations of Nigerian crude and condensate export," the company said.

Nigerian crude oil exports to the United States peaked in 2007 and have since steadily decreased to zero since shale oil production increased.

The state oil company said exports of 2.26 million barrels per day in August, the last full month for which data are available, were 12.4 percent higher than the previous month. Overall, oil production rose 6.8 percent in August.

Nigeria is among the largest African members of the Organization of Petroleum Exporting Countries. OPEC, in its market report for November, said Nigerian exports were on the rise in general, including to the United States.

"U.S. imports of Angolan and Nigerian crude, which have been weaned off, were 130,000 b/d above what they were in July," the monthly market report said.