West Texas Intermediate futures for September delivery declined to $46.72 (-0.85%), while Brent crude dropped to $51.72 (-0.94%). Iranian Oil Minister Bijan Namdar Zanganeh said the country's output could increase by 500,000 barrels a day within a week after international sanctions are lifted and by 1 million barrels a day within a month after that. According to the Iran oil ministry's news agency, sanctions against Tehran should be lifted by the end of November.

Greater exports from Iran combined with OPEC's market share protection policy would weigh on prices, Zanganeh said.