Irish telecoms and media tycoon Denis O'Brien has once again increased his stake in Independent News & Media, the Guardian reported Thursday.

O'Brien has upped his holdings of the media group to 19.35 percent, from 18.05 percent, the owner of the Independent and Independent on Sunday said. He bought 5 percent of the company two years ago, and has been building up his stake in INM steadily over the past months.

INM Chief Executive Anthony O'Reilly remains the Dublin-based company's biggest shareholder, with more than 26 percent. He has called O'Brien a “dissident shareholder,” and said he will do his best to not sell Independent titles, despite O'Brien's calls for INM to sell loss-making titles and his criticism of strategy and performance. The titles are “substantial calling cards,” building up the brand as it grows its global reach, O'Reilly said, according to the Guardian.

O'Reilly's son, Gavin O'Reilly, is chief operating officer of INM, and also president of the World Association of Newspapers' executive committee and board.