The gay left-wing commentator Johann Hari has apologised for an “error of judgement” over his use of quotes in interviews.

The Orwell prize-winning journalist, who writes for the Independent and Attitude magazine, was accused of plagiarism and ‘churnalism’ after bloggers spotted that he had used old quotes in interviews without attributing them.

Bloggers discovered that a 2004 interview with the Italian Marxist Antonio Negri used identical quotes to those in a 2003 book, Negri on Negri, by Anne Dufourmantelle.

In another example, Yahoo.com Ireland editor Brian Whelan found that a 2010 interview with Israeli journalist Gideon Levy used sentences taken from a column written by Mr Levi a year before.

In some instances, Mr Hari had described subjects’ hushed tones and pregnant pauses when reporting the quotes.

Twitter users accused him of deceit, poor journalism and plagiarism and a series of spoof posts poked fun by imagining historical events as told to him.

Other journalists were quick to criticise and the former political editor of the Observer, Gaby Hinsliff, tweeted: “i’m rarely shocked by stuff journalists do, but tbh this J Hari thing does it for me. quotes are sacrosanct. end of…”

Mr Hari, who is now facing calls to hand back his Orwell prize, apologised in an Independent article today but said he had added the quotes for “intellectual accuracy”.

He also claimed that interviewees would sometimes sound “incomprehensible or confusing” in speech, so he would lift passages “written or said more clearly elsewhere”.

He wrote: “So I’ve thought carefully about whether I have been wrong here. It’s clearly not plagiarism or churnalism – but was it an error in another way? Yes. I now see it was wrong, and I won’t do it again.

“Why? Because an interview is not just an essayistic representation of what a person thinks; it is a report on an encounter between the interviewer and the interviewee.

“If (for example) a person doesn’t speak very good English, or is simply unclear, it may be better to quotes their slightly broken or garbled English than to quote their more precise written work, and let that speak for itself.”

Hari added that he had focused on the “intellectual accuracy” of the quotes and not the “reportorial accuracy of describing their ideas in the words they used on that particular afternoon”.

But he said: “That was, on reflection, a mistake, because it wasn’t clear to the reader.

“I’m sorry, and I’m grateful to the people who pointed out this error of judgement. I will make sure I learn from it.”

Independent editor Simon Kelner has backed Mr Hari, writing on Twitter that the newspaper has not received any complaints about him in ten years.