LOS ANGELES — Google Inc. said yesterday that it has launched a music search service in China that allows legal online access to music in a forum backed by some record labels and supported by advertising revenue.

Paid music downloads in China are virtually nonexistent, and Apple Inc.'s iTunes digital music store is not offered there. Downloadable pirated versions of songs are widely available free online.

Google's service, Music Onebox, directs users to www.Top100.cn, a site that names basketball star Yao Ming as an investor, to download or stream music for free. Users outside China are blocked from accessing the music.

Top100.cn is a Beijing-based Web site that already has licensing agreements with about 100 labels. Talks are ongoing with Sony BMG and Warner Music Group Corp. to become partners.

"This legal music service will help users avoid dead links, slow downloads, inaccurate search results, and poor quality or incomplete songs," Google said in a statement.

Google said it is not participating in any of the advertising revenue from the site.