NEW YORK - U.S. mortgage rates fell for a fourth consecutive week, with 30-year mortgages remaining below 5 percent, a closely watched mortgage survey showed Thursday.

The lowest mortgage rates in decades and high affordability helped the hard-hit housing market find some footing last year after a three-year slump. Attractive rates bode well for the housing market, but the sector remains highly vulnerable to setbacks and reliant on government intervention.

Interest rates on U.S. 30-year fixed-rate mortgages, the most widely used loan, averaged 4.98 percent for the week ended January 28, down from the previous week's 4.99 percent, according to a survey released by Freddie Mac (FRE.P) (FRE.N), the second-largest U.S. mortgage finance company.

That is below the year-ago level of 5.10 percent. Eight weeks earlier the rate hit 4.71 percent, the lowest since Freddie Mac started the survey in 1971.

Last year was rough on the housing market, Frank Nothaft, Freddie Mac vice president and chief economist, said in a statement.

LOW RATES, LIMITED APPEAL

The appeal of attractive rates on home loan refinancing activity appears to be losing steam.

The Mortgage Bankers Association on Wednesday said U.S. mortgage applications fell for the first time in four weeks, with relatively low interest rates having limited appeal for a shrinking universe of qualified borrowers who see the benefit of refinancing home loans.

Mortgage rates are linked to yields on Treasuries and yields on mortgage-backed securities.

Freddie Mac said the 15-year fixed-rate mortgage averaged 4.39 percent in the latest week, down from 4.40 percent the prior week. For rates table, double-click on

Interest rates on other types of mortgages also fell.

One-year adjustable-rate mortgages (ARMs), were 4.29 percent in the latest week, down from 4.32 percent the prior week. The rate on the 5/1 ARM, set at a fixed rate for five years and adjustable each following year, was 4.25 percent, compared with 4.27 percent a week earlier.

A year ago, 15-year mortgages averaged 4.80 percent, the one-year ARM 4.90 percent and the 5/1 ARM 5.27 percent.

(Editing by Theodore d'Afflisio)

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