The Pakistani journalist Ahmed Rashid has told the BBC of his disappointment that parts of his work appear to have been plagiarised by President Bush.
Mr Rashid said that it was never a compliment when politicians plagiarise ideas or comments from journalists without acknowledging their work.
A US website said last week that Mr Bush's book was remarkably similar to previously published writings.
Mr Bush released his memoir Decision Points earlier this month.
The former president has not commented on the allegations, but his publisher was reported last week as saying that if there were similarities in his work with that of other writers, it only confirms the accuracy of Decision Points.
Part of Mr Bush's book recounts a meeting between Afghan President Hamid Karzai and a Tajik warlord on the Afghan president's inauguration day.
The former president used the encounter as an example of hope for the future of the country.
"When Karzai arrived in Kabul for his inauguration on 22 December - 102 days after 9/11 - several Northern Alliance leaders and their bodyguards greeted him at an airport," he wrote.
"As Karzai walked across the tarmac alone, a stunned Tajik warlord asked where all his men were.
"Karzai responded: 'Why, General, you are my men. All of you who are Afghans are my men.'"
The US-based Huffington Post website said that this account and the quote were lifted almost verbatim and without attribution from a New York Review of Books article by Ahmed Rashid.
The website said that his book "borrows heavily" from investigative reporter Bob Woodward's account Bush at War, which the White House criticised as inaccurate when it was published in 2002.
It said he also appears to take chunks from a book written by his former press secretary Ari Fleischer.
In a statement released to the BBC News website Mr Rashid - who regularly writes for the BBC - said that he was not happy that his work had been copied.
"You would expect an American president's researchers to come up with an acknowledgement, at least if they wanted to lift somebody else's articles or comments," he said.
"Unfortunately neither President Bush nor his researchers paid me that compliment nor have they apologised since the quote was spotted some days ago."
Mr Rashid said that he had been "offered all sorts of advice" to rectify the matter.
"My children and their friends and some journalist colleagues want me to sue him," he joked, "but I told them I would do no such thing."
"Other friends and colleagues have said it was a big joke, but in all seriousness I am not laughing.
"It is never a compliment when politicians plagiarise ideas or comments from journalists without acknowledging their work. Unfortunately it happens all the time."