Single-family home prices dipped modestly in April, pointing to signs of stabilization in the battered housing market at the start of the spring buying season, a closely watched survey said on Tuesday.

The S&P/Case-Shiller composite index of 20 metropolitan areas dipped 0.1 percent on a seasonally adjusted basis. A Reuters poll of economists had forecast a decline of 0.2 percent.

On a non-seasonally adjusted basis, however, the index rose 0.7 percent, its first advance in eight months, the report said.

The seasonally adjusted numbers show that much of the improvement reflects the beginning of the spring-summer home buying season, David Blitzer, chairman of the index committee at Standard & Poor's, said in a statement.

It is much too early to tell if this is a turning point or simply due to some warmer weather.

The excess amount of houses for sale, ongoing foreclosures, tight credit and weak demand have kept the housing market on the ropes even as other areas of the economy start to recover.

Prices in the 20-city index fell 4 percent year over year, slightly worse than expectations for a drop of 3.9 percent.

(Reporting by Leah Schnurr; Editing by Padraic Cassidy)