EU regulators should look into the book settlement that Google Inc reached with a group of U.S. writers and publishers last October because the deal will create a de facto monopoly, European opponents to the book deal said on Friday.

Google's plan to digitize millions of books is aimed at resolving a lawsuit filed in 2005 by the Authors Guild. Critics say it will allow the U.S. Internet search-engine giant to dominate the digital book market in its infancy.

Earlier this month, Germany and France took their case against the settlement to the Manhattan federal court, which will hold a fairness hearing on October 7. Inc has also argued against the plan.

A hearing held by the European Commission on the matter on September 7 and attended by interested parties and Google officials failed to answer critics' questions, the groups said in a letter to EU Internal Market Commissioner Charlie McCreevy, Competition Commissioner Neelie Kroes and six other commissioners.

Signatories to the letter include Microsoft-sponsored lobbying group ICOMP, the German Publishers and Booksellers Association, German lobbying group SuMa and CEPIC, which represents about 1,000 picture associations, agencies and libraries in Europe.

We believe (the settlement) is unacceptable in its present form as it violates the rights of copyright holders and authors and would lead to a de facto monopoly, the groups said.

They queried whether the proposed book database could be accessed only by Google's search engine and if this was the case, whether it would reinforce the company's market share in search advertising. This should be a concern for European antitrust regulators, the critics said.

Google rejected the criticism, saying it had responded to all the questions fielded at the hearing and had met numerous times with interested parties.

To say we chose not to answer questions is simply wrong. We have always been happy to answer questions about the settlement, including from organizations like ICOMP, the company said in a statement.