Federal Reserve Chairman Ben S. Bernanke defended the central bank’s record stimulus program under questioning from lawmakers, telling them that ending it prematurely would endanger a recovery hampered by high unemployment and government spending cuts.

“A premature tightening of monetary policy could lead interest rates to rise temporarily but would also carry a substantial risk of slowing or ending the economic recovery and causing inflation to fall further,” Bernanke said in a testimony to the Joint Economic Committee of Congress in Washington.

Bernanke lamented the human and economic costs of an unemployment rate at 7.5 percent nearly four years into the recovery from the deepest recession since the Great Depression, and said the Fed’s easing is providing “significant benefits.” His comments echoed remarks by William C. Dudley, president of the Federal Reserve Bank of New York, who said in an interview that it would take three to four months before policy makers will know whether a sustainable recovery is in place.

Fed officials “need to see inflation expectations remain in a desired range, they need to see that the peak home-buying season goes as well as it can, and they need to see that we have absorbed the bulk of the huge fiscal consolidation” before they reduce the pace of purchases from $85 billion a month, said Lou Crandall, chief economist at Wrightson ICAP LLC in Jersey City, New Jersey.

The Fed aims to drive down interest rates and encourage investors to seek higher returns in riskier assets, broadening the impact of the central bank’s stimulus. Lower borrowing costs for households and businesses allow them to refinance and pare debt, freeing up more cash for spending or dividends.

The Fed chairman said the central bank is on the watch for financial imbalances that may result from its low interest-rate policy. “Our sense is that major asset prices like stock prices and corporate bond prices are not inconsistent with the fundamentals,” Bernanke said in the question-and-answer period following his remarks.

 “Recognizing the drawbacks of persistently low rates, the FOMC actively seeks economic conditions consistent with sustainably higher interest rates,” the Fed chairman said. “Unfortunately, withdrawing policy accommodation at this juncture would be highly unlikely to produce such conditions.”