Gay journalist Johann Hari is facing more accusations of plagiarism as the Orwell Prize committee said he had returned his 2008 award but not the £2,000 prize money.

Earlier this month, the Independent columnist published a lengthy apology for plagiarising numerous interviews but said he stood by the articles which won him the Orwell Prize.

He said he was handing back the award as an “act of contrition” for other mistakes.

Today, the prize committee said he would have been stripped of the honour, had he not handed it back before they could announce their decision.

The committee added that an article which won him the prize had been found to contain “substantial” stolen material.

The committee said in a statement: “[We] concluded that the article contained inaccuracies and conflated different parts of someone else’s story (specifically, a report in Der Spiegel).

“The council ruled that the substantial use of unattributed and unacknowledged material did not meet the standards expected of Orwell prize-winning journalism.”

It added that Hari had returned the award by courier with no note of explanation but had not returned the prize money.

The statement added: “The council would like to apologise to those who entered the Journalism Prize 2008. We also apologise to the judges, for not being able to conduct a fair assessment at the time. It is also grateful to those who persisted in examining Hari’s articles and brought the discrepancies to the council’s attention.”

Hari, who is also a contributing editor to gay magazine Attitude, was the subject of an investigation by the Independent’s founding editor, Andreas Whittam Smith., who found he had also used a pseudonym, David Rose, on Wikipedia to attack those who criticised him.

The journalist has not been sacked. Instead, he will take a four-month period of unpaid leave to retrain in America.

Writing in the newspaper, Hari said: “I would like to apologise again to my readers, my colleagues and the people hurt by my actions. I know that some of you have lost faith in my work. I will do everything I can now to regain it. I hope, after a period of retraining, you will give me the chance.”