WASHINGTON — Federal Reserve officials stuck with the pace of their $600 billion Treasury bond-buying program last month because the economy wasn’t improving fast enough to make a noticeable dent in unemployment.

Spending by consumers and businesses had improved heading into the final month of 2010, and Congress was on the verge of enacting a tax-cut package that would bolster the economy, Fed officials said. That made them more confident the economic recovery would gain momentum, according to minutes of the Fed’s closed Dec. 14 meeting .

Risks still loomed, the minutes said, particularly a weak housing market and spending cuts and layoffs from state and local governments. So the Fed voted 10-1 to stick with its plan to buy the bonds through June to try to lower interest rates, spur spending and lift stock prices.

Still, with the economy gaining strength, the risks of deflation have “receded somewhat over recent months,” the Fed minutes said. Deflation is a widespread drop in prices, wages and in the values of homes and stocks. A fear of deflation was one reason the Fed launched the bond-buying program.

With unemployment high and factories still operating well below capacity, “slack” in the economy will keep a lid on inflation, Fed officials said.

Fed officials said they would regularly review the pace and the size of bond-buying program in the months ahead.

The Fed’s main reason for launching the bond-buying program was to drive down unemployment, now at 9.8 percent. The Fed said that progress on that front has been disappointingly slow.