New York's main contract, West Texas Intermediate for delivery in September, was down 35 cents at USD 106.75 a barrel in afternoon trade while Brent North Sea crude for October eased 38 cents to USD 109.52.
"The market is taking a wait-and-see approach," Victor Shum, managing director at IHS Purvin and Gertz in Singapore, told AFP.
The US Energy Information Administration last week said crude stockpiles shrank to 360.5 million barrels in the week to August 9, the lowest since January. A decline in stockpiles supports crude prices as it suggests a pick-up in demand.
Prices are getting support from fears about a tightening of supplies from the Middles East owing to sporadic violence in Egypt as well as strikes in Libya that have hampered oil production and shipping operations.
"The tense situation in Egypt and Libya continues to be a cause for uncertainty and is providing a floor for oil prices," Shum said.