"It's obvious that if you have high prices it'll affect demand, so you have to do some market balance," Malam Mele Kyari, head of crude oil marketing at Nigeria's state oil firm NNPC and also the country's OPEC representative, told Reuters.

"OPEC will do everything to stabilize, to balance the market but I'm sure you're also aware that there's a limit to what they can do. You must have the spare capacity," Kyari said.