Oil prices are now at an 18-month low due to weaker demand amid a global financial crisis.
US light crude for December delivery settled at $US63.22 a barrel on Monday, down 93 cents - its lowest settlement price since 29 May, 2007. London Brent crude settled down 64 cents to $US61.41 a barrel.
Oil prices are down by almost 60% since reaching $US147.27 a barrel on 11 July. Demand has since fallen as the financial crisis spreads.
The Organization of the Petroleum Exporting Countries agreed on Friday to cut production by 1.5 million barrels per day.
