The University of California is joining Google Inc.'s book-scanning project, throwing the weight of another 100 academic libraries behind an ambitious venture that's under legal attack for alleged copyright infringement.

The deal to be announced Wednesday covers all the libraries in UC's 10-campus system, marking the biggest expansion of Google's effort to convert millions of library books into digital form since a group of authors and publishers sued last fall to derail a project launched 20 months ago.

We think this is a pretty significant step forward, said Adam Smith, the group product manager overseeing Google's book-scanning initiative.

UC joins three other major U.S. universities, Stanford, Michigan and Harvard, that are contributing their vast library collections to Google's crusade to ensure reams of knowledge written on paper makes the transition to the digital age. The New York Public Library and Oxford University also are allowing portions of their libraries to be scanned.

The project is expected to last years and cost tens of millions of dollars, a bill that Google is footing. It's something Google can easily afford, given the nearly 8-year-old company has already amassed nearly $10 billion in cash.

Google's motives aren't entirely altruistic. The Mountain View, Calif.-based company wants to stock its search engine with unique material to give people more reasons to visit its Web site, the hub of an advertising network that generates most of its profits.

The endeavor has riled authors and publishers because Stanford, Michigan and Harvard are all allowing Google to create digital copies of books still protected by copyright. UC also is giving Google access to the copyrighted material.

Only so-called public domain books no longer protected by copyrights will be shown in their entirety. Google doesn't plan to show anything more than a few snippets from copyrighted material, a fair use approach that the company believes is allowed under U.S. law.

Both the Association of American Publishers and Authors Guild, the two trade groups suing Google, contend the company shouldn't be allowed to stockpile digital versions of copyrighted material without permission.

Although the lawsuits aren't directly targeting the university libraries, UC's alliance with Google irritated the publishing community.

It's a curious decision to make, given the pending litigation and legal uncertainties surrounding the project, said Allen Adler, vice president of legal and government relations for the Association of American Publishers.

UC's move also disappointed the Association of Learned and Professional Society Publishers, a group representing not-for-profit publishers. We are concerned and we aren't happy, said Nick Evans, member services manager for the group. There are no guarantees how this information might be used in the future.

The lawsuits are expected to remain in the evidence-gathering stage through the remainder of this year.

Google's arguments in the dispute received a recent boost in Germany earlier this summer after a publisher in that country abandoned its effort to prevent its copyrighted works from being copied.

UC's libraries already have been involved in another book-scanning initiative called the Open Content Alliance that's spearheaded by Yahoo Inc. and Microsoft Corp., two of Google's biggest rivals. That project, which continues, focuses exclusively on books without copyright protection.

The decision to link up with Google to widen the scope of UC's book scanning was made by university president Robert Dynes without a vote by the board of regents. There are so many benefits to this, said Jennifer Colvin, a spokeswoman for UC's library. We respect copyrights, but we also want to give full access to our public domain material.