WASHINGTON (AP) — Long-term U.S. mortgage rates continued to climb this week, reaching their highest level in more than four years and denting prospective home purchasers' prospects amid the spring buying season.

It was the third straight week of increases for long-term mortgage rates. Mortgage buyer Freddie Mac says the average rate on 30-year, fixed-rate mortgages jumped to 4.58 percent from 4.47 percent last week. By contrast, the benchmark rate averaged 4.03 percent a year ago.

The average rate on 15-year, fixed-rate loans rose to 4.02 percent from 3.94 percent last week.

Spiking rates on U.S. Treasury bonds, driven by rising commodity prices, helped lift long-term mortgage rates to their highest level since August 2013.