The magazine's announcement comes one day after palace officials announced they'll be taking legal action against French magazine Closer -- owned by the same parent company, Mondadori -- for publishing photographs of Kate sunbathing topless on a private vacation with Prince William on Friday.
Mondadori spokeswoman Carmen Mugione told CNN that Chi plans to print an additional 26 pages of photographs of the royal couple.
"It is a story worth publishing in an extraordinary edition because it shows in a natural light the everyday life of a very famous contemporary young couple in love," Alfonso Signorini, Chi's editor-in-chief, said in an e-mail statement to CNN. "The fact that they happen to be the future king and queen of England certainly makes it more interesting and current, and in line with today's concept of monarchy."
Currently touring Southeast Asia as part of the Diamond Jubilee celebration, William and Kate, both 30, are "furious" following the release of the images, a source close to the couple told Us Weekly.
A palace rep said Friday, "St James' Palace confirms that legal proceedings for breach of privacy have been commenced today in France by The Duke and Duchess of Cambridge against the publishers of Closer Magazine France."