Online bookseller Amazon.com Inc. is warning a federal judge that Internet search leader Google Inc. will be able to gouge consumers and stifle competition if it wins court approval to add millions more titles to its already vast digital library.

The harsh critique of Google’s 10-month-old settlement with U.S. authors and publishers emerged this week in a 41-page brief that Amazon filed in an attempt to persuade U.S. District Judge Denny Chin to block the agreement from taking effect.