Prices were also under pressure from the deal on Syria's chemical weapons and reports signaling the return of Libyan crude to the market, where production and exports had slowed to a trickle due to labor conflicts and technical glitches.
"The Middle East risk premium has started to dissolve in the crude oil prices after concerns about a possible military action in Syria eased," analysts at Sucden Financial Research in London said in a note. "Libyan oil production is expected to increase to 400,000-450,000 barrels a day in the next few days as the El Sharara field has restarted."
Investors will also be monitoring fresh information on U.S. stockpiles of crude and refined products.
Data for the week ending Sept. 6 are expected to show a draw of 1.5 million barrels in crude oil stocks, while gasoline stocks are expected to remain unchanged according to a survey of analysts by Platts, the energy information arm of McGraw-Hill Cos.
The American Petroleum Institute will release its report on oil stocks later Tuesday, while the report from the Energy Department's Energy Information Administration the market benchmark will be out on Wednesday.
The contract for November delivery for Brent crude, the benchmark for international crudes used by many U.S. refineries, was down 55 cents to $109.52 a barrel on the ICE Futures exchange in London.
In other energy futures trading in New York:
Wholesale gasoline fell 0.5 cent to $2.7015 per gallon.
Natural gas rose 1.9 cents to $3.757 per 1,000 cubic feet.
Heating oil declined 1.29 cents to $3.0508 per gallon.
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Pamela Sampson in Bangkok contributed to this report.