In a surprise to Wall Street, minutes from the Fed's December policy meeting, published on Thursday, showed a growing reticence about further increases in the central bank's $2.9 trillion balance sheet, which it expanded sharply in response to the financial crisis and recession of 2007-2009.

"Several (officials) thought that it would probably be appropriate to slow or to stop purchases well before the end of 2013, citing concerns about financial stability or the size of the balance sheet," the minutes said, referring to the narrower group of voting Fed members.

Investors picked up on the report's hawkish tone, with stock prices drifting lower after the announcement, while the U.S. dollar extended gains against the euro. Yields on the 30-year Treasury bond hit 3.12 percent, their highest levels since May.

"The minutes of the Federal Reserve's December monetary policy meeting revealed a somewhat surprising level of concern among the ranks of central bankers regarding the long-term impact of the bank's asset purchase program, or quantitative easing," said Omer Esiner, chief market analyst at Commonwealth Foreign Exchange in Washington D.C.