A former political advisor to previous First Minister David Trimble has resigned from a newspaper following allegations of plagiarising his column.
Freelance writer Steven King has left the Irish Examiner and apologised to the paper's editor and readers.
The editor, Tim Vaughan said he was "surprised, angry, saddened and disappointed" by what Mr King did.
He is alleged to have copied material published by Brendan O'Neill, editor of the British online magazine Spiked.
Mr King, who is now a director of APCO, the global public affairs and communications firm, is quoted in Wednesday's Examiner admitting he was wrong.
"I must apologise wholeheartedly if any material was unoriginal, any research was insufficiently thorough and if any attributions to other authors were insufficient," said Mr King.
"I could make all sorts of excuses: the pressure of work; a once fantastically happy marriage almost shattered by mental illness; the death of a partner which is extremely difficult to accept. But the buck stops with me."
During the 1990s Mr King was a personal advisor to Ulster Unionist leader David Trimble at some of the most crucial moments in the peace process.
A review of all Mr King's columns in the last year was conducted and in seven instances they appeared to include material very similar to that previously published by Mr O'Neill.
Following the investigation, Mr Vaughan accepted the columnist's resignation.
"It is not a fool-proof system as there has to be a lot of trust with regular freelance contributors such as columnists," said Mr Vaughan.
"That is the same for every newspaper, and if that trust is breached, action has to be taken.
"Steven is an extremely bright man and I find it difficult to understand why he resorted to this.
"It is a real pity because he was a brilliant, always interesting columnist, but unfortunately, and regrettably, something went very wrong along the way."
Spiked editor Mr O'Neill said he was happy the issue was "sorted out quickly and efficiently".