The new allegation against 48-year-old Zakaria levelled by The Washington Post was, however, refuted by The Daily Beast, which said the Indian-American author did contain a citation to what he quoted in his 2008 book The Post-American World.
Zakaria's book contains a quote from former Intel Corp chief executive Andy Grove about the United States economic power, the Post said. It said that the first edition of Zakaria's book, which became a bestseller, makes no mention of the comment's source, nor does a paperback version published in 2009.
In fact, the Post said, Grove's comment was published three years earlier in Three Billion New Capitalists: The Great Shift of Power to the East, by former commerce department official Clyde V Prestowitz, who is attached with the Economic Strategy Institute, an eminent think tank. However, Zakaria defended his book.
In an interview to the Post he called the allegation "totally bogus" because the book "is not an academic work where everything has to be acknowledged and footnoted."
"People are piling on with every grudge or vendetta," Zakaria told the paper.
Allegations and counter-allegations are flying in the US media after Zakaria was suspended recently for a month by his employers CNN and Time magazine in the wake of charges that his column about gun laws for Time's August 20 issue includes a paragraph that is remarkably similar to one Jill Lepore wrote in April for a New Yorker article on the National Rifle Association. Zakaria apologised for it.
In his interview to The Washington Post, Zakaria said, "As I write explicitly (in the book), this is not an academic work where everything has to be acknowledged and footnoted."
The book contains "hundreds" of comments and quotes that are not attributed because doing so, in context, would "interrupt the flow for the reader," he said.
He compared his technique to other popular non-fiction authors. "Please look at other books in this genre and you will notice that I'm following standard practice," he told the paper.
"I should not be judged by a standard that's not applied to everyone else," he added.
The Post, which claims that Zakaria appears to have published without attribution a passage from Prestowitz's 2005 book, said on Monday that his weekly column would not appear this month.
Prestowitz, the paper said, contacted Zakaria about the Grove quote when Post-American World was published four years ago but received no response.
"Prestowitz said he also mentioned the lack of attribution to his editor and agent, but he doesn't know if they raised the issue with Zakaria or his publisher," the daily said.
Writing for The Daily Beast, writer and columnist David Frum, argues that such an allegation from The Washington Post is not true.
"The 2009 paperback does contain a citation to Prestowitz: footnote 11, page 262. We photocopied the page this very afternoon at the DC Public Library's central branch... We couldn't locate a physical copy of the 2008 hardcover edition in time, but Amazon's 'look inside' feature shows Prestowitz there in hardcover too, also in footnote 11, page 262," he wrote.
"It would be a strange reflection on journalistic practice if a Washington Post reporter - sent to investigate Fareed Zakaria's journalistic methods - issued such a damaging accusation without first independently verifying it," wrote Frum, who is a contributing editor at Newsweek and The Daily Beast and a CNN contributor. He is the author of seven books, including most recently his first novel Patriots, which was published in April 2012.
However, Baltimore Sun columnist David Zurawik questioned the defence of Zakaria by Frum.
"Stop with the lame excuses: A researcher did it, and Zakaria just signed off on it; he left the attribution out because he didn't want to harm the flow of his writing; if it is plagiarism, it's the lowest form and not worthy of any significant punishment; it's a grey area; lots of people do it," he wrote.