Independent News & Media, an Irish publishing company that prints The Independent titles in Ireland and the UK, has ramped up its war of words with its largest outside shareholder, branding him a "dissident" who is actively trying to destabilise the company and destroy value for its other investors.

Irish mobile phone entrepreneur Denis O'Brien raised his stake in the group yesterday to 22.15%, prompting the reaction from the company this morning. He has been critical of the company's board in the past and urged it to sell off its loss-making titles, which include The Independent in the UK.