O'Brien's latest onslaught came on Friday at the Global Economic Forum in Dublin.
It followed a recent flurry of criticism by the shareholder, who has long been calling for the group to close The Independent. O'Brien is also at odds with IN&M chief executive Gavin O'Reilly and the board over the repayment of its €200m debt.
O'Brien said: "There's no point in us as a company subsidising a newspaper that really nobody wants to read in the United Kingdom. It's not a relevant newspaper any more and this newspaper's going to be closed at Christmas."
A spokesman for IN&M said: "Denis O'Brien has made clear his hostility. But this is his most outspoken criticism yet and it does nothing to motivate the staff who work at the newspaper."
This article was first published on mediaweek.co.uk