Best-selling author and philanthropist Greg Mortenson, hospitalized for heart surgery, canceled a scheduled appearance in Massachusetts, a group sponsoring the event says.

Mortenson is the subject of recent media allegations of financial mismanagement and literary fraud, and Montana's attorney general has launched an inquiry into a charity run by Mortenson.

Officials with the Massachusetts Conference United Church of Christ, a group sponsoring the May 3 event, say in a statement that they were told Mortenson was having surgery in Bozeman, Mont., to repair a hole in his heart and couldn't make the Worcester speech.

"Given the surgery and recuperation time, Mortenson's agent said it was impossible for him to fulfill his engagement," Massachusetts Conference United Church of Christ said.

Mortenson is co-author of "Three Cups of Tea." CBS' "60 Minutes" and author Jon Krakauer reported that Mortenson lied about events in several parts of his book and may have financially benefited from money donated to his charity to build schools in Pakistan and Afghanistan.

Krakauer wrote in his recently published "Three Cups of Deceit" that Mortenson embellished events in his books and about the number of schools he built. Krakauer also reported that charity proceeds were spent on chartered jets, equipment and advertising for Mortenson's books, even though the charity doesn't receive any royalties.

In a recent interview with Outside magazine, Mortenson said he had done nothing wrong.

"Our decision to sponsor Greg Mortenson's appearance in Worcester focused on providing an opportunity for laity and clergy to be inspired and challenged by Mortenson's work in Afghanistan and Pakistan, and to share with him their questions and concerns," said Associate Conference Minister Susan Dickerman.

Worcester Children's Chorus of 50 young people from the area was slated to sing and proceeds from the event were to be shared with the Worcester Area Mission Society's after-school programs, Dickerman said.

Organizers said they would provide refunds for tickets sold for $51.50.

Peru State College in Nebraska recently rescinded its invitation to Mortenson after a "60 Minutes" report, and school spokeswoman Regan Anson said the school "cannot set him out as an example."