Brent crude fell below $100 a barrel for the first time since July on signs economic growth will slow, curbing demand. West Texas Intermediate oil was little changed before a report that may show a U.S. supply gain.
West Texas Intermediate oil slipped to the lowest level this year as Chinese manufacturing expanded less than forecast and U.S. federal spending cuts were set to be triggered, bolstering concern that fuel demand will decline.
OPEC crude output rose for the first time in six months as rising Libyan production outpaced a cut by Saudi Arabia, which has implemented a program aimed at curbing excess supply and supporting prices.
Crude rose the most in a month on forecasts that U.S. gasoline supplies dropped after Hurricane Sandy forced the shutdown of East Coast refineries and as Americans went to the polls to pick a president.