Yahoo Inc. late on Wednesday said it had begun testing a service to search information on password-protected subscription sites such as LexisNexis, known as the "deep Web."

The move comes as Yahoo, Google Inc. and Ask Jeeves Inc. rush to give Web searchers access to ever more information -- from books, blogs and scholarly journals to news, products, images and video.

The service, http://search.yahoo.com/subscriptions, called Yahoo! Search Subscriptions, allows users to search multiple online subscription content sources and the Web from a single search box.

Yahoo Search Subscriptions will initially offer content from such providers as ConsumerReports.org, The Wall Street Journal Online, The New England Journal of Medicine and Forrester Research Inc.

Users can see content from the sites they subscribe to, while nonsubscribers have the option of paying to see it.

Content providers, for their part, get access the vast audience of Web search users, said David Mandelbrot, Yahoo's vice president of search content.

Sources like Factiva, LexisNexis' pay-as-you-go AlaCarte service and Thomson Gale will be added in the coming weeks.

Yahoo, which does not currently have revenue-sharing relationships with the information providers, more than a year ago started a content-acquisition program and plans to add more sources to its subscription search site, said Mandelbrot.