Businessman Denis O’Brien has said he is going to seek punitive damages against Dublin communications company Red Flag Consulting and five personal defendants because of the suggestion that he may have illegally gained possession of a USB stick containing documents created by the company.

In his latest affidavit to the court, the businessman has given new details about the circumstances that existed at the time he came into possession of the device, which he claims contains documents about him gathered by Red Flag that were designed to damage him.

In his first affidavit Mr O’Brien said he engaged professional investigators to establish if there was a campaign against him and the source of this campaign, and that the investigation established that Red Flag was involved in disseminating information relating to him by way of the dossier contained on the USB stick.

He said that during the course of the investigation he received an anonymous package containing the USB stick and that the receipt of the device may have been prompted by the investigation.

In his latest affidavit, Mr O’Brien said that in early September 2015 he instructed his solicitors to retain competent persons to investigate who might be involved in a campaign against him.

Podcast: Denis O'Brien's case against Red Flag explained

His solicitors, he said, told him they had engaged a chartered accountant, John Whelehan, formerly of PwC but now working with a consultancy firm in Kiev, Ukraine. Mr Whelehan started an investigation based on publicly available information on Mr O’Brien and his businesses and relevant media commentary “to see if the source of this campaign could be identified”.

“In the event the memory stick was received anonymously in the interim and Mr Whelehan did not then provide a report.”

Mr O’Brien said the password for the USB stick was written inside the envelope. He said the envelope was discarded and the USB stick sent for forensic examination. He said he did not understand the allegation made in a replying affidavit on behalf of the defendants which alleges or suggests that he might have received the USB stick illegally.

He said the entirely unsubstantiated allegation would be “relied upon by me and my advisers in seeking aggravated, exemplary and/or punitive damages in these proceedings.”

In his affidavit on behalf of the defendants, Red Flag chief operating officer Garret Doyle, who is not a defendant, said it now appeared that Mr O’Brien did not in fact learn from an investigator that Red Flag had disseminated information about him by way of the dossier. Nor did it appear that Mr O’Brien was maintaining, as originally said, that the investigations carried out by an investigator may have prompted the receipt of the USB stick.

“If this latter version of events is correct, then it appears that [Mr O’Brien] made an ex parte application for an Anton Pillar order and other exceptional reliefs on the basis of an affidavit that was lacking in candour.”

Since Mr O’Brien’s original approach to the court, the matter had been before the court 10 times, more than a hundred solicitors letters had been exchanged, significant costs amounting to hundreds of thousands of euro had been incurred, and Red Flag, Mr Doyle said, had lost one significant and valuable project as a result of the proceedings.

Mr O’Brien rejected the claim that he had been lacking in candour and said that the wording of his first affidavit could have been clearer. He had learned of Red Flags involvement from the USB stick.

The other defendants are Karl Brophy, Seamus Conboy, Gavin O’Reilly, Brid Murphy and Kevin Hiney. The hearing continues.