West Texas Intermediate oil fell for the sixth time in seven days amid forecasts that U.S. refineries reduced operating rates last week, allowing crude supplies at Cushing, Oklahoma, to rebound from near six-year lows.

Refineries probably operated at 92.8 percent of capacity on Aug. 1, down 0.7 percentage point from the prior week, according to a Bloomberg survey before a government report tomorrow. The announcement last week that a Coffeyville, Kansas, refinery that gets oil from Cushing may be offline for most of August sent WTI to a four-month low. Brent slipped on reports that Kurdish fighters in Iraq retook border towns seized by Islamic militants.

"We're all anxious about tomorrow's data," said Bob Yawger, director of the futures division at Mizuho Securities USA Inc. in New York. "WTI has been supported by the fall in Cushing supplies this year. Coffeyville being offline may change the whole formula and we may see a supply gain."

WTI for September delivery dropped 48 cents, or 0.5 percent, to $97.81 a barrel at 10:27 a.m. on the New York Mercantile Exchange. Futures touched $97.09 on Aug. 1, the lowest intraday level since Feb. 5. The volume of all futures traded was 28 percent below the 100-day average. Prices are down 0.6 percent this year.

Brent for September settlement slipped 72 cents, or 0.7 percent, to $104.69 a barrel on the London-based ICE Futures Europe exchange. Volumes were 10 percent higher than the 100-day average. The European benchmark crude traded at a $6.88 premium to WTI, down from $7.12 yesterday.