World oil prices were mixed Wednesday as traders reacted to a surprise increase in crude reserves in the United States, which is the world's biggest energy consumer.

That Hurricane Dean spared major U.S. energy production facilities in the Gulf of Mexico helped pull down the prices.

New York's main oil futures contract, light sweet crude for delivery in October, slipped 31 cents to close at 69.26 dollars per barrel. The price had earlier fallen as low as 68.63 dollars, the lowest level since June 28.

In London, the price of Brent North Sea crude for October delivery added one cent to settle at 68.70 dollars per barrel.

The U.S. Department of Energy said Wednesday that U.S. crude inventories rose by 1.9 million barrels in the week ending Aug. 17.