Johann Hari will return to the Independent as a columnist in “four to five weeks”, according to editor Chris Blackhurst.

He told the Leveson Inquiry that everything written by Hari will be “heavily looked at” by editorial staff and members of the public, and that he will no longer interview individuals for the paper.

The disgraced journalist will return to the publication after four months of unpaid leave and a self-funded trip to study ethics at universities Columbia and NYU in New York.

It was discovered last year that Hari had been fabricating details of interviews, including lifting quotes from other interviews and work published by his subjects, and editing profiles of professional rivals on Wikipedia.

“He should have known what he was doing was wrong but nobody told him,” said Blackhurst. “In terms of plagiarism it wasn’t as stark and severe as the Jayson Blair case. He wasn’t fabricating hard news as far as I was aware.”

He described the “shock” caused by the scandal on Independent staff and the impact on the paper’s reputation but said: “I don’t think we covered it up at all”. He added “nobody had complained” to the paper before Hari’s actions were outed by several bloggers and online commentators.

An internal investigation into Hari’s conduct was carried out by Independent founding editor Andres Whittam Smith but will not be made available to the public as it is considered to be a disciplinary review.

Blackhurst pointed out that he had only been appointed as editor of the Independent two days before Hari’s plagiarism allegations were made public, moving from the Evening Standard where he had been city editor since 2002.