Microsoft and Yahoo are joining forces to make an unusual partnership to go up against Google in digitizing many of the world's great books.

The grouping, called the Open Content Alliance (OCA) is making its pitch just as Google and the publishing industry are getting bogged down in litigation over its ambitious plans to create a free for all digital library.

The OCA, unveiled earlier this month by a group of digital archivists and backed by Yahoo, HP and Adobe, says it has also signed up Microsoft and more than a dozen major libraries in North America, Britain and Europe.

Danielle Tiedt, general manager of Microsoft's MSN Search, said the world's largest software maker would fund the digital duplication of 150,000 old books over the next year.

Last week five major book publishers filed a US lawsuit that aims to block Google's plan to scan books from five of the world's libraries; Oxford, Harvard, Stanford and Michigan and the New York Public Library.