A defamation case by businessman Denis O'Brien over an article in the Irish Daily Mail in January 2010 is under way at the High Court.

Mr O’Brien is claiming the article, about his appearance in RTÉ news reports on the relief effort after the earthquake in Haiti, accused him of hypocrisy motivated by self interest.

The Daily Mail is denying the article was defamatory.

Mr O’Brien said Paul Drury's column in the paper was nasty, spiteful and offensive.

He believed it was a malicious attack, suggesting he had used the disaster in Haiti as a PR exercise.

Mr O’Brien today outlined the scenes of devastation he witnessed in Haiti and his efforts to help Digicel staff and others after the disaster killed more than 300,000 people.

He said he spent less than ten minutes in the company of RTÉ reporter Charlie Bird in the aftermath of the 2010 earthquake.

He said comments in the article that he "kept popping up" in RTÉ reports indicated the journalist knew nothing about what was going on in Haiti.

Mr O'Brien said he was not thinking about the Moriarty Tribunal in the weeks and months after the earthquake.

Suggestions that he was using it as a public relations exercise could not be further from the truth, he said.

Describing it as a crescendo of nastiness towards the end of the article, Mr O'Brien said to suggest he was following Mr Bird around Haiti like a lap dog could not be further from the truth.

The article was offensive and insulting, he added.

Before the earthquake, he visited Haiti every five to six weeks and since the earthquake he has been there 59 times.

His was a different form of capitalism, which not only sought to make a profit but also invested in education and healthcare to try to improve a country, he said.

This, he said, was unlike other foreign direct investment, which "just robbed the place and did no good whatsoever".

He said the shocking part of this article, which commented on how his business interests operated in Haiti, was a lack of knowledge about economic development, he said.

As lines of the article were read to him he described one as "another box in the kidneys to criticise me for investing in a poor country".

In response to points made in the article that he had taken out a series of ads criticising the cost of the Moriarty Tribunal, including what tribunal lawyers spent, he said this was "childish fun" on his part.

Asked if he had any reason to disbelieve what the article contained was Mr Drury's opinion he said: "Well he wrote it, it must be his opinion".

He agreed that allowing someone to express an opinion was the basis of freedom of the press.

However, he said there were certain facts and research that could be done on which to base opinion.

He did not accept there was a very clear difference between an opinion piece and a news article.

Asked if it was not clear that comment pieces were generally beside the editorial, he said he did not know how a newspaper was put together, despite having significant business interests in media companies in Ireland.

He said the article was littered with mistakes and the tone of it was "smart arsed".