The publisher of an authorised best-seller about North Korean defector and human rights activist Shin Dong-hyuk has said it is anxious for an "accurate understanding" of the facts after he retracted substantial parts of his story.
Penguin Books publicity director Louise Braverman said the publisher was consulting with Blaine Harden, whose book Escape From Camp 14 came out in 2012.
Viking, a Penguin imprint, "has been apprised that there were some inaccuracies in the story Shin Dong-hyuk, the subject of the book, told the author", a statement said. "We are working with the author on an accurate understanding of the facts."
Mr Harden's book spent several weeks on The New York Times hardcover and paperback best-seller lists, and, according to Ms Braverman, has been published in 27 languages. More than 200,000 copies are in print in the US alone.
According to Mr Harden, a former Washington Post reporter, Mr Shin has acknowledged to him that he changed some key details and had apologised.
"In light of my conversation with Shin," Mr Harden wrote on his website, "I am working with my publisher to gather more information and amend the book."
He said he has pressed Mr Shin to "explain why he had misled me" during interviews for the book.
Publishers rarely fact-check books, citing time and expense, and instead rely on the authors.
North Korea tried to discredit Mr Shin late last year as it fought a United Nations General Assembly resolution that backed the findings of a ground-breaking UN commission of inquiry into Pyongyang's human rights abuses.
Human rights groups say the UN inquiry was based on interviews with scores of North Korean defectors. "Its findings are still valid," said Brad Adams, Asia director for Human Rights Watch.
The organisation gave Mr Shin an award for extraordinary activism last year and said he was "regarded as the single strongest voice on atrocities taking place in North Korea".
Mr Shin was travelling and could not be reached for comment. He was expected to arrive in Seoul from the US today, said Greg Scarlatoiu, executive director of the Washington-based Committee for Human Rights in North Korea.
"Every one of us have stories, or things we'd like to hide," Mr Shin said in an apology for the inaccuracies in recounting his past in his latest Facebook post, giving few details.
He said he may or may not be able to continue his work of trying to eliminate North Korea's political prison camps but urged others to keep fighting. "These will be my final words and this will likely be my final post," he said.
Mr Shin's story originally drew widespread attention because he said he had lived in a high-security political prison camp in North Korea from his birth until his escape through an electrified fence. He describes himself on Facebook as "the only known person born in a North Korean prison camp that escaped and survived to tell the tale".
Mr Harden's statement said he passed Mr Shin's new information to The Washington Post. Its report over the weekend said Mr Shin now says he was transferred around the age of six to a lighter-security prison camp with his mother and brother.
It was there, not the harsher camp, where he informed authorities about an escape attempt by his mother and brother, who were executed. He now says he was later transferred back to the harsher camp.
"The fundamental building blocks of his story have remained the same, although I am fully aware of the differences between (the two camps)," Mr Scarlatoiu said.
"Still, born and raised in a camp, he was subjected to forced labour, induced malnutrition and torture. He informed on his mother and brother, who were executed. He escaped from the camp, and lived to tell his story. None of that has changed."
North Korea's government denies the existence of the harsh political prison camps, and human rights groups and others rely on both information from defectors and satellite images for information. The North Korean government did not allow the UN commission of inquiry to visit the country for its work.
The commission of inquiry's report, released early last year, detailed abuses including mass starvation and forced abortions and recommended that North Korea's human rights situation be referred to the International Criminal Court. The commission of inquiry also sent a letter to young leader Kim Jong Un warning him that he could be held accountable.
That alarmed North Korean authorities, and its diplomats circulated a DVD called Lie And Truth: Who Is Shin Dong-Hyuk? in an attempt to discredit him by using footage of his own father speaking out against him. But Mr Shin said the DVD merely proved that his father was still alive.