NEW YORK (CNN/Money) - Long-term mortgage rates continued their upward trend, a move that could temper rising home values, Freddie Mac said Thursday.

"Concern that long-term interest rates are too low and comments from Fed officials this week helped push mortgage rates higher this week," said Frank Nothaft, Freddie Mac vice president and chief economist.

"However, as mortgage rates begin to trend upward we expect the rate of house price appreciation to begin to slow to perhaps seven or eight percent nationally this year."

The average rate on 30-year fixed-rate mortgages rose to 5.79 percent in the week ended Thursday, with an average 0.7 point payable up front, up from 5.69 percent the previous week.

A year earlier, the average rate on the 30-year fixed-rate loan stood at 5.59 percent.

The 15-year mortgage rate averaged 5.33 percent, with a 0.6 percentage point payable up front, up from 5.22 percent in the previous week.

A year earlier, the 15-year rate averaged 4.88 percent.

Five-year adjustable-rate mortgages (ARMs) averaged 5.17 percent, with an average 0.7 point payable up front, up from 5.05 last week. There was year earlier figure since Freddie Mac only began tracking this mortgage rate at the start of this year.

One-year ARMs averaged 4.14 percent, down slightly from last week's 4.16 percent, with 0.8 of a point payable up front. At this time last year, the one-year ARM rate averaged 3.47 percent.

Freddie Mac's (down $0.51 to $63.24, Research) average mortgage rates are based on a survey of 125 lenders nationwide.