Oil slumped 5 percent to near six-year lows on Monday, accelerating its months-long rout after Goldman Sachs slashed its short-term price forecasts and Gulf producers showed no signs of curbing output.
U.S. crude oil closed down $2.29 at $46.07, its lowest since April 2009.
Brent was last down about $3 to $47.24 a barrel, after dropping as low as $47.18, the lowest since March 18, 2009.
Analysts at Goldman Sachs cut their three-month forecasts for Brent to $42 a barrel from $80 and for the U.S. West Texas Intermediate contract to $41 from $70 a barrel. The bank cut its 2015 Brent forecast to $50.40 a barrel from $83.75 and U.S. crude to $47.15 a barrel from $73.75.