(CNN) Shin Dong-hyuk's horrific descriptions of his time in a North Korean prison camp became a best-selling book , made him a key witness before the United Nations and grabbed headlines around the world.

He was one of the most high-profile North Korean defectors, winning several human rights awards and inspiring a documentary as his memoir was translated into 27 languages.

Now the publisher of the book and its author say Shin -- who claims to have been born in and escaped from a North Korean prison camp -- has revealed that parts of the story he told weren't true. Shin may have spent most of his life in North Korea at a different prison camp, rather than the total control zone that formed the title of his biography.

Shin's accounts of his time in the gulag have been widely reported in interviews with media including CNN. He also wrote an opinion piece describing his experiences for CNN Digital.

Blaine Harden, author of the book "Escape from Camp 14," said in a statement on his website over the weekend that Shin had changed "key parts of his story."

"On Friday, Jan. 16, I learned that Shin Dong-hyuk, the North Korean prison camp survivor who is the subject of 'Escape from Camp 14,' had told friends an account of his life that differed substantially from my book," Harden said. "I contacted Shin, pressing him to detail the changes and explain why he had misled me."

Harden declined to provide additional details to CNN, but published a lengthy explanation on his website. A Washington Post story based on information Harden said he had provided to the newspaper said "the most horrific details" of Shin's story "still stand," but some of the times and places of the events in his accounts were wrong.

"From a human rights perspective, he was still brutally tortured, but he moved things around," Harden told the Post, where he worked as a reporter for 28 years.

Shin did not immediately respond to a request from CNN for comment. In a post on his Facebook page, he doesn't go into details about the purported discrepancies, but he includes a link to the Post's story and apologizes to his supporters.

"This particular past of mine that I so badly wanted to cover up can no longer be hidden, nor do I want it to be," he says. "To those who have supported me, trusted me and believed in me all this time, I am so very grateful and at the same time so very sorry to each and every single one of you."

Inconsistencies highlighted

Shin "significantly revised details of his early life," said Harden in a statement. The inaccuracies include the following:

• In the book, in his United Nations testimony and in interviews with media including CNN, Shin has detailed torture and abuse he claimed occurred in a notorious prison known as Camp 14. Shin told Harden on Friday that he'd actually been transferred with his mother and brother to a less restrictive prison camp, Camp 18, when he was six years old. It was there, not at Camp 14, where Shin now says he witnessed authorities execute his mother and brother.

• Shin had previously said that he had lived his entire life in Camp 14 before escaping in 2005. He now says he escaped from Camp 18 twice before -- in 1999 and 2001, wrote Harden in his statement. During his second escape attempt from Camp 18, he was caught in China and repatriated to North Korea. First, he was sent to Camp 18 and later transferred to Camp 14 for torture and punishment, wrote Harden.

• Shin now says he was 20 years old when he was tortured as a punishment for escaping, wrote Harden. His original account indicated that he was tortured when he was 13 for plotting to escape. Shin had been saying that he was tortured when he was a teenager since his arrival to South Korea in 2006.

• Shin had described in the book that his finger was chopped off by an angry guard after he dropped a sewing machine in Camp 14. Now, Shin told Harden that his finger was mangled as a guard pulled out his fingernails as punishment for escaping.

I altered some details that I thought wouldn't matter. I didn't want to tell exactly what happened in order not to relive these painful moments all over again. Shin Dong-hyuk

"When I agreed to share my experience for the book, I found it was too painful to think about some of the things that happened," Shin told Harden. "So I made a compromise in my mind. I altered some details that I thought wouldn't matter. I didn't want to tell exactly what happened in order not to relive these painful moments all over again."

Shin told Harden that he thought that dates, places and circumstances were not all that significant, according to the author's statement.

Challenges with North Korea accounts

Accounts from North Korean defectors are often difficult to confirm, with lack of documents and the regime's general secrecy.

Harden stated that he was working with the publisher to amend the book. It's unclear what action the book's publisher will take in response to the discrepancies in Shin's story.

"Viking, the publisher of "Escape From Camp 14" by Blaine Harden, has been apprised that there were some inaccuracies in the story Shin Dong-hyuk, the subject of the book, told the author," Penguin Books spokeswoman Louise Braverman said in a written statement Sunday. "We are working with the author on an accurate understanding of the facts.

In a video posted last year on a website that carries pro-Pyongyang propaganda, Shin's father denied that his son was ever in a prison camp.

Human rights activists argue that changes in Shin's account do not ultimately affect his testimony, saying they still believe he was tortured and that his story highlights the horror of prison camps.

The New York Times reported Sunday that Shin said he had held back about revealing inaccuracies in his story out of concerns that it could hurt his advocacy work.

"I dithered because friends feared the damage my coming out might do to the movement for North Korean human rights," he said, according to the Times.

In his Facebook post, Shin said he was not sure if he would be able to continue his efforts to end political prison camps in North Korea.

"But instead of me, you can all still fight," he said. "I still have faith in you."