New York: The US federal court overseeing Google Inc.'s settlement over its book-scanning programme is giving authors four more months to opt out of the deal and review its potential pitfalls.

Instead of a May 5 deadline, the court ruled on Tuesday that authors now have until September 4 to review the agreement.

Under the Google Print Library Project, snippets from millions of out-of-print but copyright-protected books have been indexed online by Michigan and other libraries. Google has called the project, which also scans public-domain works, an invaluable chance for books to receive increased exposure.

But in a class-action suit filed in 2005, the Authors Guild alleged that Google was "engaging in massive copyright infringement." Within weeks, publishers also sued.