Oil prices tumbled nearly 5 percent on Friday as U.S. consumer confidence fell unexpectedly in August, Xinhua reported.
Oil's losses came after the Reuters/University of Michigan said that the consumer sentiment index decreased in August, boosting doubts about demand recovery and pressuring oil price to its three- week low of 67.12 U.S. dollars a barrel.
Light, sweet crude for September delivery plummeted 3.01 dollars, or 4.3 percent, to settle at 67.51 dollars a barrel on the New York Mercantile Exchange, ending the week with a 4.8 percent drop.
Meanwhile, the dollar gained against the euro after three days of decline, reducing the appeal of crude as an alternative investment to hedge against inflation.
In London, Brent Crude for September delivery dropped 1.07 dollars to settle at 72.41 dollars a barrel on the ICE Futures exchange.