Mortgage rates rose this week on inflationary and geopolitical concerns, Freddie Mac said in its latest Primary Mortgage Market Survey. The 30-year, fixed-rate mortgage increased to 4.81% for the week ending March 24 from 4.76% last week. That's still lower than the 4.99% recorded a year ago. Meanwhile, the 15-year, fixed-rate mortgage hit 4.04%, compared to 3.97% a week earlier and 4.34% a year ago. Freddie said the five-year, Treasury-indexed hybrid mortgage rate averaged 3.62%, up from 3.57% seven days prior and down from 4.14% last year. In addition, the one-year ARM climbed to 3.21% in the most recent survey, up from 3.17% last week. Frank Nothaft, Freddie Mac vice president and chief economist, outlined some of the inflationary pressures that buoyed mortgage rates. "The 12-month growth rate in the consumer price index rose 2.1% in February, compared to 1.6% in January; however, most of the increase was due to food and energy prices, which tend to be volatile. The core index rose 1.1%, slightly up from 1% in January," he said. Bankrate also released mortgage rate data Thursday, showing the 30-year FRM now sits at 4.96%, up from 4.91% a week earlier. The 15-year FRM inched up to 4.16% from 4.12%, and the 5/1 ARM rate hit 3.78%, up from 3.74%. "Mortgage rates increased, but only slightly, as investors digest world events and assess the potential impact on global economic recovery," Bankrate said. "The outlook for economic growth, inflation, and a desire to avoid market volatility are the key drivers of bond yields and mortgage rates on a day-to-day basis. Mortgage rates are closely related to yields on long-term government bonds." Write to Kerri Panchuk.