Google, the increasingly powerful internet search engine, could overhaul the way books are sold with a planned service that allows users to search full texts and buy titles online.

The company founders, Sergey Brin and Larry Page, are at the Frankfurt Book Fair this week wooing publishers in the hope of convincing them to provide their catalogues for inclusion in the service, Google Print.

It has already signed up several big names including Penguin, Houghton Mifflin, Blackwell and Oxford University Press.

Since Mr Brin and Mr Page founded Google from a college dormitory six years ago, the service has become a cultural phenomenon with users increasingly relying on it to find information. It handles more than 200m searches a day and has added functions including a news service which aggregates stories from the world's media and Froogle, a shopping marketplace.

Google Print searches books according to key words and throws up a handful of titles at the top of the results.

Entering "trekking in Ecuador", for instance, throws up three titles next to a book icon. Users can then click on any one and are taken through to a digitised version of a selected page of the book.

Publishers choose how much of the text is made available for users to browse through. In the case of The Mountaineers Books company, 16 pages of its Trekking in Ecuador is online. Users are not able to print the pages off.

The book can be further interrogated with other key words, allowing users to find out, for instance, if a particular region of Ecuador is included.

Links are provided to the appropriate page of various online booksellers including Amazon.com, barnesand-noble.com and in this case directly to the publisher.

Google has no financial relationship with any of the book sellers and makes money from advertising carried on the pages of text.

Relatively few books have been included so far and the service is still having teething problems. Not every search for trekking in Ecuador is throwing up the book options in its search results.

Susan Wojcicki, the director of product development at Google, said the book service was a "natural step in Google's evolution. It's part of the same mission we have had since launching six years ago to organise the world's information. Our goal in making books available is to improve and enhance our searches".

There were no plans to begin selling books directly, she added. "Our plan is to be a search engine." Google licenses the search technology to Amazon and Ms Wojcicki said that relationship would not be affected.

Publishers are able to sign up online and send their books to Google, where they are scanned and added to the search index for no cost. Ms Wojcicki said publishers and authors "will be able to attract new readers and increase book sales". To entice publishers, it plans to share advertising revenues with them.

Wall Street has been watching for Google to introduce new services since it joined the stock market amid a huge fanfare in August.

In April, Google turned up the heat on Yahoo! and Microsoft by announcing plans to launch a free email service, called Gmail, that would offer huge amounts of extra capacity.

The service, however - which is still being tested - caused concern about privacy issues because of the way it would make revenues - emails would be scanned by computer for keywords and then carry targeted ads.

Analysts were yesterday uncertain how much of an impact Google Print would have on the company's bottom line.

Its shares have risen more than 60% since the flotation.