U.S. Federal Reserve Chairman Ben Bernanke attends a press conference after a Federal Open Market Committee (FOMC) meeting in Washington D.C., capital of the United States, Jan. 25, 2012. (Xinhua/Zhang Jun)

The U.S. Federal Reserve announced no further steps in its monetary policy, but pledged to keep the exceptionally low levels of key interest rate for even a longer time to boost economic recovery.

The U.S. economy has been "expanding moderately", the Federal Open Market Committee (FOMC) said in a statement released after a two-day meeting.

The statement noted that the unemployment rate remains high, growth in business fixed investment has slowed, and the housing market remains depressed.

The Fed's policy board expects to maintain a "highly accommodative stance" for monetary policy to support a stronger economic recovery. It noticed the inflation has been subdued in recent months, and longer-term inflation expectations have remained stable.

The Fed "currently anticipates that economic conditions -- including low rates of resource utilization and a subdued outlook for inflation over the medium run -- are likely to warrant exceptionally low levels for the federal funds rate at least through late 2014," said the FOMC statement.

The latest announcement extended the time frame for the ultra-low key interest rate by about 18 months. The Fed said last summer that the key interest rates would not be raised from its current range of 0-0.25 percent before mid-2013. It slashed the overnight federal funds rate to near zero in December 2008 to stimulate economic growth as financial crisis intensified.

The U.S. central bank also decided to continue its program to extend the average maturity of its holdings of securities as announced in September.

The Fed's statement was approved on a 9-1 vote. Jeffrey Lacker, president of the Richmond regional Fed bank, voted against the new time period for a rate increase.

The U.S. economy has shown signs of improvement recently, especially in its labor market where the unemployment rate dropped to 8.5 percent last month. Homebuilders confidence also rose, according to data released last week.

The Fed stressed the "significant downside risks" from global financing strains and cautioned that economic growth over coming quarters would be "modest" and the unemployment rate would decline only gradually toward the desired level.

In its latest quarterly economic forecast, the central bank predicted the U.S. economy would expand by 2.2 percent to 2.7 percent in 2012, down from its November estimate range of 2.5 to 2.9 percent. Unemployment rate would stand between 8.2 to 8.5 percent, better than the previous projection in November.

As a big step to enhance communications with the public and make policy decisions more transparent, the Fed published for the first time charts to give more detailed information about the FOMC members' expectations for the timing of interest rate actions.

Five of the 17 participants hold that the appropriate time for the increase of target federal funds rate from its current range would be the year of 2014. Six members considered the appropriate level for the key interest rate would be above 1 percent in 2014, while other 11 members preferred to keep the rate under 1 percent till that time.