West Texas Intermediate crude fell from a three-week high. The U.S. benchmark widened its discount to Brent as the European Union warned that Russia risks growing isolation over the downing of Malaysian Air flight MH17.

The EU pressed President Vladimir Putin to speed a probe into the downing of the plane as European foreign ministers met in Brussels to discuss further sanctions against Russia. U.S. crude supplies may have decreased 2.9 million barrels last week, according to a Bloomberg survey before a government report tomorrow.

"The geopolitical situation definitely affects Brent more," said Bob Yawger, director of the futures division at Mizuho Securities USA Inc. in New York. "You have storage numbers tomorrow. It's a headline market."

WTI for August delivery, which expires today, slid 26 cents, or 0.3 percent, to $104.33 a barrel at 10:53 a.m. on the New York Mercantile Exchange. The contract closed at $104.59 yesterday, the highest level since July 1. The more actively-traded September crude contract was down 31 cents at $102.55. Volume was 0.2 percent above the 100-day average.

Brent for September settlement was unchanged at $107.68 a barrel on the London-based ICE Futures Europe exchange after earlier gaining as much as 0.7 percent. The volume of all futures was 21 percent below the 100-day average.