U. S. mortgage rates fell below 5 percent again, a key level that may boost home loan demand, according to a closely watched mortgage survey on Thursday.

The rate for 30-year fixed U. S. home loans is reported to fell to 4.97 percent for the week ended today from 5.01 percent, mortgage finance company Freddie Mac revealed in a statement today. Mclean, Virginia-based company revealed 15-year rate was 4.34 percent on an average.

The figures are well below the 5.16 percent level the previous year, but above the record low of 4.71 percent in early December. Freddie Mac started the survey in 1971.

The lowest mortgage rates in decades and high affordability supported the wounded housing market find some footing last year after a three-year slump. Attractive rates proved bliss for the setback prone housing market.

"Although the Federal Reserve has reaffirmed the plan to discontinue the agency MBS purchase program in March, they have given assurances that they will step in on an 'as needed' basis to provide support to the markets," David Adamo, CEO of Luxury Mortgage, in Stamford, Connecticut revealed.

The Mortgage Bankers Association's index of mortgage applications fell 1.2 percent in the week ended Feb. 5, with the purchase gauge decreasing 7 percent and the refinancing gauge increasing 1.4 percent.