Rates for U.S. 30-year mortgages climbed from the lowest level on record after Federal Reserve officials pledged to keep their benchmark interest rate near zero through at least late 2014 to help bolster the economy.

The average rate for a 30-year fixed loan rose to 3.98 percent in the week ended today from 3.88 percent, the lowest in records dating to 1971, Freddie Mac said in a statement. The average 15-year rate increased to 3.24 percent from 3.17 percent, according to the McLean, Virginia-based mortgage- finance company.