Yahoo search engine ' biggest on net'

In a major expansion, Yahoo says its online search engine index now spans more than 20 billion web documents and images, nearly double the material scanned by rival Google.

Yahoo’s expansion does not necessarily mean it produces more useful results than Google, which has long been considered the internet’s most comprehensive database. But the breakthrough gives the Sunnyvale, California-based company the bragging rights to a widely watched measurement for assessing the power of an internet search engine.