A federal judge on Monday dismissed a civil lawsuit against author Greg Mortenson, calling claims “flimsy and speculative’’ that the humanitarian and his publisher lied in his best-selling “Three Cups of Tea’’ and “Stones Into Schools’’ books to boost sales.

The lawsuit by four people who bought Mortenson’s books claimed that they were cheated out of about $15 each because the books were labeled as nonfiction accounts of how Mortenson came to build schools in central Asia. They had asked U.S. District Judge Sam Haddon to order Mortenson and publisher Penguin Group (USA) to refund all the money collected from Mortenson’s book sales.

The readers from Montana, California and Illinois filed the lawsuit after “60 Minutes’’ and author Jon Krakauer reported last year that Mortenson fabricated parts of those books.

The plaintiffs said Mortenson, co-author David Oliver Relin, Penguin and Central Asia Institute were involved in a fraud and racketeering conspiracy to build Mortenson into a false hero to sell books and raise money for CAI, the charity Mortenson co-founded.

Haddon wrote in his ruling that their racketeering allegations “are fraught with shortcomings’’ and the plaintiffs’ “overly broad’’ claims that they bought the books because they were supposed to be true were not supported in the lawsuit.

The ruling is good news for Mortenson and his charity after the Montana attorney general earlier in April announced a $1 million agreement to settle claims that Mortenson mismanaged the institute and misspent its funds. The agreement removes Mortenson from any financial oversight and overhauls the charity’s structure, but it does not address the books’ contents.

Mortenson, who was traveling to Pakistan and Afghanistan, said in an email Monday to The Associated Press that the past year has been challenging as he faced the Montana investigation, the lawsuit, the media reports, plus surgery for a small hole doctors found in his heart.