Google has launched a service designed to search TV content from US broadcasters including PBS, NBA, Fox News and C-SPAN.

The Google Video beta enables users to search across the closed captioning content of a growing number of TV programmes that the firm began indexing in December 2004.

Entering a query will return a list of relevant programmes with still images and text excerpts from the exact point in the programme where the search word or phrase was spoken, the search giant claimed.

"What Google did for the web, Google Video aims to do for television," said Larry Page, Google co-founder and president of products.

"This preview release demonstrates how searching television can work today. Users can search the content of TV programmes for anything, see relevant thumbnails, and discover where and when to watch matching programmes.

"We are working with content owners to improve this service by providing additional enhancements such as playback."

The service offers a preview page which displays up to five still images and five short text segments from the closed captioning of each programme. It also provides information on upcoming episodes and shows when a programme will next be aired.

Viewers can search within a show for specific words or search more broadly for programme details and episode information.

Google said that the beta release of its video offering does not include Google AdWords advertising or playback options.