WASHINGTON » Average U.S. mortgage rates rose only slightly this week and continued to hover near record lows, a trend that has helped boost home sales and refinancing.

Mortgage buyer Freddie Mac said today that the rate on the 30-year fixed mortgage edged up to 3.41 percent, from 3.37 last week. Three weeks ago, the rate touched 3.36 percent. That’s the lowest level on records dating to 1971.

The average rate on the 15-year fixed mortgage, often used for refinancing, rose to 2.72 percent. That’s up from last week’s record low of 2.66 percent.

The rate on the 30-year loan has remained below 4 percent all year, helping drive a modest housing recovery. And rates have fallen even further since the Federal Reserve started buying mortgage bonds in September to try to encourage more borrowing and spending.

Home sales have increased from last year, and prices are rising more consistently in most areas. Builders are more confident and starting more homes. Lower rates have also persuaded more people to refinance. That typically leads to lower monthly mortgage payments and more spending.

This week brought more positive news on the housing front. U.S. sales of new homes jumped last month to the highest level in more than two years, the Commerce Department said Wednesday. And slightly more Americans signed contracts last month to buy homes, the National Association of Realtors reported today.

Still, the housing market has a long way to a full recovery. And many people are unable to take advantage of the low rates, either because they can’t qualify for stricter lending rules or they lack the money to meet larger down payment requirements.

To calculate average mortgage rates, Freddie Mac surveys lenders across the country on Monday through Wednesday of each week.

The average doesn’t include extra fees, known as points, which most borrowers must pay to get the lowest rates. One point equals 1 percent of the loan amount.

The average fee for 30-year loans was 0.7 point, unchanged from last week. The fee for 15-year loans also held steady, at 0.6 point.

The average rate on a one-year adjustable-rate mortgage slipped to 2.59 percent from 2.60 percent. The fee for one-year adjustable rate loans remained at 0.4 point.

The average rate on a five-year adjustable-rate mortgage was unchanged at 2.75 percent. The fee also was unchanged, at 0.6 point.