Prices of U.S. single-family homes fell 18.6 percent in February from a year earlier but the rapid pace of decline slowed, perhaps indicating the housing market may be nudging closer to a bottom, according to Standard & Poor's/Case-Shiller Home Price Indices released on Tuesday.

The composite index of 20 metropolitan areas fell 2.2 percent in February from January, S&P said in a statement. The depreciation on a month-over-month was above expectations based on a Reuters survey of economists, but below on a year-over-year basis. The 20-city index dates back to 2000.

Of the 20 metro areas, 10 showed record rates of annual decline, and 15 reported declines in excess of 10 percent versus February 2008.

S&P said its composite index of 10 metropolitan areas declined 2.1 percent in February from January for an 18.8 percent year-over-year drop. The 10-city index dates to 1988.

For the first time in 16 months, the annual decline of the 10-city and 20-city composites did not set a record.

While the declines in residential real estate continued into February, we witnessed some deceleration in the rate of decline in some of the markets, David M. Blitzer, Chairman of the Index Committee at Standard & Poor's, said in a statement.

(Reporting by Julie Haviv; Editing by James Dalgleish)