Oil prices retreated Thursday on weakened concerns over Syrian and rising market speculations about US Federal Reserve's stimulus tapering.

No attack against Syria has materialized and Britain and France said they were inclined to wait for the results of a United Nations investigation into Syria's alleged use of chemical weapons.

On the previous trading day, the possibility that US and other western countries may take military action against the Syrian government triggered concerns over oil supplies in the Middle East, where one-third of the world's crude is pumped, driving Brent oil prices to a six-month high.

US real gross domestic product increased at an annual rate of 2.5 percent in the second quarter this year, the US Commerce Department announced Thursday. This is a welcome acceleration from an initial estimate of 1.7 percent released last month, which turned out better than market expectations.

Meanwhile, the number of Americans who initially applied for jobless benefits declined 6,000 to 331,000 in the week ending Aug. 24 from an upwardly-revised figure of 337,000 in the prior week, the Labor Department reported Thursday.

Investors view the pair of good data as a stronger sign of recovery of the US economy, believing that continued improvement in the labor market may propel the US Federal Reserve to scale back its massive monetary stimulus later this year.

Light, sweet crude for October delivery fell 1.30 dollars to settle at 108.80 dollars a barrel on the New York Mercantile Exchange.

While Brent crude for October delivery lost 1.45 dollars to close at 115.16 dollars a barrel.