Oil dropped to a one-month low after U.S. crude inventories surged the most since March as production and imports rebounded from Hurricane Isaac.

Futures decreased as much as 3.3 percent after the Energy Department said supplies rose 8.53 million barrels last week, more than eight times what was projected in a survey. Imports arrived at the highest rate since January and output rose. Crude fell before the report on speculation Saudi Arabia is moving to reduce prices.

Crude oil for October delivery declined to $91.90 a barrel at 11:15 a.m. on the New York Mercantile Exchange.

Brent oil for November settlement fell $3.43, or 3.1 percent, to $108.60 a barrel on the London-based ICE Futures Europe.