WASHINGTON, Feb 27 (Reuters) - U.S. 30- and 15-year mortgage rates dipped to new record lows for a second straight week in the week ending Feb. 28, Freddie Mac said on Thursday in its latest survey.

U.S. 30-year mortgage rates stood at an average 5.79 percent in the week, breaking the previous record low of 5.84 percent last week. Freddie Mac began tracking 30-year mortgages in 1971.

Fifteen-year mortgages stood at an average 5.14 percent, down from the previous record of 5.21 percent last week. The corporation began tracking 15-year mortgages in 1991.

One-year adjustable rate mortgages (ARM)) were almost unchanged at an average 3.83 percent, compared with last week's record low of 3.81 percent.

"Debilitating forces, such as looming war clouds in the Middle East, declining consumer confidence and other issues, are making an economic rebound difficult. And when the economy is weak, interest rates tend to follow suit," Frank Nothaft, Freddie Mac chief economist, said in a statement. "Low rates will continue to keep the housing industry busy this year, and indications are that there is a good chance home sales may set yet another record in 2003.”

Earlier on Thursday, the Commerce Department said U.S. January new home sales fell 15.1 percent to an annual rate of 914,000 units, the lowest rate in a year.