U.S. 30-year fixed-rate mortgages hit a record low for the third straight week as concerns over the euro zone weighed on the economy, mortgage financier Freddie Mac said Thursday.

The average 30-year mortgage fell to 3.79 percent, down from the previous record low of 3.83 percent in the prior week, and below 4.61 percent in the prior year.

The European debt crisis overshadowed improving economic indicators for the U.S. and allowed Treasury bond yields and fixed mortgage rates to ease for another week, said Frank Nothaft, Freddie Mac's chief economist.

Positive indicators included U.S. industrial production rising 1.1 percent in April, the largest gain since December 2010, and consumer sentiment reaching its highest reading since January 2008, according to the University of Michigan. Housing starts also rose to an annual rate of 717,000 in April, beating forecasts, and the NAHB/Wells Fargo Housing Market Index reported the highest homebuilder confidence level in over four years.

The rate for 15-year fixed mortgages fell to 3.04 percent, from 3.05 percent in the previous week, and 3.80 percent in the prior year. Five-year Treasury-indexed adjustable rate mortgages (ARMs) rose to 2.83 percent, from 2.81 percent in the prior week, but below the 3.48 percent in the previous year.

One-year Treasury-indexed ARMs averaged 2.78 percent, up from 2.73 percent in the previous week, but below 3.15 percent in the prior year.