New York's main contract, light sweet crude for delivery in November sank 33 cents to USD 91.04 a barrel and Brent North sea crude for November delivery shed 49 cents to USD 109.96 in morning trade.
Doubts expressed yesterday by Charles Plosser, head of the Fed's Philadelphia branch, over the economic impact of the QE3 bond-buying program announced earlier this month dragged markets down, analysts said.
"A high-profile figure in the form of... Plosser questioned the effect QE3 would have, particularly on labour markets," IG Markets said in a report.
"Many traders feel central bank stimulus is merely a sticking plaster for a broken leg, and that much more needs to be done to send the global economy safely on the road to recovery."
Plosser's comments also triggered a large selloff in the US stock markets late Tuesday, with the Nasdaq, Dow Jones Industrial Average and S&P 500 tanking after his speech.