Benchmark West Texas Intermediate crude for February delivery dropped 41 cents to close at US$98.91 a barrel on the New York Mercantile Exchange. Trading was thinner than usual because of the approaching holidays.
Last week, oil rose nearly three per cent, largely because of signs of improvement in the U.S. economy.
Positive economic news and a corresponding increase in demand have some analysts predicting that oil will soon top $100 a barrel for the first time since Mid-October.
Brent crude, a benchmark used to price international crudes used by many U.S. refiners, fell 21 cents to US$111.56.
In other energy futures trading, wholesale gasoline was flat at US$2.78 a U.S. gallon (3.79) litres, heating oil lost two cents to US$3.06 a gallon and natural gas added five cents to US$4.46 per thousand cubic feet.
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