The Seattle Post-Intelligencer reported Thursday that Amazon announced last month that "on-demand" publishers who don't use Amazon subsidiary BookSurge would not be allowed to sell their books directly on Amazon.com.

"If they succeed in doing this, they'll have basically seized the supply chain, and they can pretty much call the shots and pay less to publishers for the books, which means less money going to the authors in many cases," said Paul Aiken, executive director of The Authors Guild in New York.

Writers' groups have complained to Amazon itself as well as to the U.S. Justice Department and the Washington state attorney general's office, the newspaper said.

The writers' groups say they are worried that Amazon will eventually control publishing for the many titles that are sold in small quantities.

"We suspect this maneuver by Amazon is far more about profit margin than it is about customer service or fossil fuels," The Authors Guild said in an April 4 e-mail to members. "We're reviewing the antitrust and other legal implications of Amazon's bold move."