Oil fell in price by almost 6% on Monday amid further indications of falling demand.
US crude settled down $US3.90 at $US63.91 per barrel as global demand slowed. London Brent crude dropped $US4.84 to settle at $US60.48 per barrel.
Oil reached a record price of $US147.27 per barrel on 11 July but has since more than halved.
Factory activity in the United States contracted sharply in October, to its lowest in 26 years.
The Institute for Supply Management said its index of national factory activity fell to 38.9 in October from 43.5 in September.
BP chief executive Tony Hayward estimated that US demand has dropped by 2 million barrels per day on the year over the last four weeks.
OPEC agreed in October to reduce output by 1.5 million barrels per day.
