The kingdom called out members for overproducing, in what was seen as a veiled threat of a price war.

Part of the issue is that members are not sticking to their pledged cuts. The Saudi minister called out Iraq, which surpassed its quota by 400,000 barrels per day in August, according to S&P Global Ratings data. Kazakhstan, which overproduced by 120,000 barrels a day, was also singled out.

OPEC said in a statement on Wednesday that a Wall Street Journal article reporting that Saudi Arabia's oil minister had said oil prices may drop to $50 if the group's members do not stick to output cuts was "wholly inaccurate and misleading".