Lawyers for a PR firm accused of being involved in a conspiracy against businessman Denis O'Brien say they are very concerned about how documents on the firm's computers made their way to Mr O'Brien.

Mr O'Brien claims Red Flag Consulting, Chief Executive Karl Brophy, Chairman Gavin O'Reilly, and three other members of staff are involved in a conspiracy to harm his interests including the recent proposed IPO of his company, Digicel.

He says they put together a dossier about him containing defamatory material. His lawyers say Mr O'Brien wants to know who commissioned them to do this.

Mr O'Brien says he received the dossier on a USB stick in an envelope delivered anonymously to him after he had engaged a private investigator to investigate a campaign against him.

Lawyers for Red Flag Consulting and the other defendants said it was a matter of extreme concern to them as to how documents on their computer systems were extracted from those computers and then delivered to Mr O'Brien.

The court heard that Mr Brophy had reported to gardaí that material had been stolen from him.

Senior counsel Michael Collins said it was a mystery as to how the documents or computer files ended up on Mr O'Brien's desk. He said he did not want to make a federal case of it but it was a big concern.

He said that although the vast majority of the documents were newspaper articles in the public domain, it was a coincidence that it seemed to be exactly the same collection of articles as Red Flag had in its possession.

He said Red Flag wanted to know how Mr O'Brien's private investigator had procured the documents.

Mr Collins said Red Flag was investigating if there had been a breach of its IT security, if they had been hacked or if someone had been persuaded to hand over the documents.

He said this was very important in the context of the bona fides of the application made by Mr O'Brien and the businessman’s account of how he got the memory stick.

Mr Collins also said it was unclear what the basis of Mr O'Brien's legal action against Red Flag was.

He asked if Mr O'Brien was saying it was unlawful for a PR firm to put together material on a public figure?

Senior Counsel Michael Cush said one of the documents contained in the dossier was a draft speech for Fianna Fáil TD Colm Keaveney.

He said Mr O'Brien's technical experts had identified words and phrases put into that speech by Mr Brophy.

And he said Mr O'Brien wanted to know who paid Mr Brophy to draft a speech for Mr Keaveney to be delivered under Dáil privilege.

Mr Cush said the newspaper articles were appendices to three documents prepared by the defendants.

He said what was involved here was a textbook conspiracy to cause harm to Mr O'Brien's interests.

He said it was calculated to cause harm to the recent proposed IPO of Mr O'Brien's firm Digicel.

The IPO was pulled by Mr O'Brien shortly before it was due to go ahead earlier this month.

Mr Cush said that compiling a set of documents to be disseminated surreptitiously may be lawful but if it was done with the intention of causing harm then it formed basis for this legal action.

He said the defendants were disseminating defamatory material and he said it was a contradiction for them to say someone had hacked into their computers.

Lawyers for Mr O'Brien were seeking to inspect Red Flag's computers and mobile devices.

However, following agreement between both sides, the court ordered that IT experts on both sides would take forensic images of all the devices involved.

This would mean there would be no further need to examine the computers themselves.

These forensic images will not be inspected but will be held by an independent solicitor to be agreed or appointed by the court.

The court ordered the memory stick was to be held by Mr O'Brien's solicitor and was not to be interfered with.

Asked by Mr Justice Colm mac Eochaidh what urgency there now was to the matter, Mr Cush said Mr O'Brien did not want any more court resources than any other citizen.

He said he did want to know who was driving this and would like to get the matter heard as soon as possible.

The case is due back before the court on 8 December to deal with whether or not Mr O'Brien is entitled to inspect the images.