The evidence given by multimillionaire Denis O'Brien to the Moriarty tribunal this week involved not one but two allegations of people conspiring against him.

In one case, that of three executives from the major Norwegian telecommunications company Telenor, Mr O'Brien alleged that his former Digifone colleague, Arve Johansen, organised false testimony for reasons of malice arising from difficulties that arose in their business dealings. Mr O'Brien has expressed doubts as to the validity of documentary evidence produced.

At issue in the allegation against Telenor is the $50,000 (€57,000) donation from Esat Digifone/Telenor to Fine Gael in December 1995, just two months after the then Fine Gael Minister for Transport Energy & Communications, Michael Lowry, announced that Digifone had won the second mobile phone licence competition.

Telenor says it agreed to make this donation on Digifone's behalf and after Mr O'Brien suggested it do so. The money was paid by the Norwegian company in order to provide confidentiality. Mr O'Brien agrees he suggested Telenor make the donation but on its own behalf. He says the Norwegians later "forced" Digifone to reimburse the payment.

The suggestion that the donation be made, whatever about its nature, was made in Oslo in December 1995, during a meeting between O'Brien and Johansen.

The money was to be paid to Fine Gael via the late David Austin, the Smurfit executive who was a close friend of O'Brien's and also a friend of Lowry's. During a telephone call, Mr Austin informed Mr Johansen that he wanted the money sent to an account in Jersey. Mr Johansen said he would need an invoice and Mr Austin sent one - for "consultancy services" and without any mention of Fine Gael.

This happened in December 1995. Mr Johansen gave evidence to this effect to the tribunal in May and June of this year.

He was adamant the money was paid on behalf of Digifone. Mr O'Brien, when he gave evidence immediately afterwards, held to his story. It was a straightforward conflict.

Some documents existed. A note in Norwegian the Austin invoice of December 14th, 1995, and written by Knut Digerud read: "Per, this has to be paid by us and invoiced as management costs to Digifone."

Per was Per Simonsen, a Telenor executive who had worked closely with Mr O'Brien on the licence bid and who, in December 1995, was working 16-hour days getting the Digifone infrastructure in place. The note by Mr Digerud was signed and dated December 20th, 1995. This evidence obviously supports Mr Johansen's evidence, that the money was always to be reimbursed. Mr O'Brien, during his evidence, complained that Mr Digerud and Mr Simonsen had not appeared to give evidence. In time they did.

The two men were not anxious to get involved in the Irish tribunal but following pressure from Dublin Castle they agreed. They gave evidence last week. Afterwards, when he returned to the witness box, Mr O'Brien accused them of lying. He said Mr Johansen, the senior executive, was the one "pulling the strings".

Mr Johansen, in new evidence last week, said that having discussed the matter with Mr Digerud he had some new information that he had not remembered when he gave evidence in May/June. He now remembered that before paying the money to Mr Austin he had brought Mr Austin's invoice and covering letter to Dublin to show to Mr O'Brien.

He was unhappy about the misleading invoice and the offshore account, and wanted further assurance from Mr O'Brien that they were doing the correct thing. (Mr Johansen said he noticed while in the Republic that a lot of businesses and people had onshore and offshore accounts.)

On December 20th, 1995, he met with the Digifone directors to discuss their project. During an aside, he showed Mr O'Brien the documents from Mr Austin and Mr O'Brien approved the payment. Mr Digerud said he witnessed this, although he didn't overhear the conversation. He said he then put his note on the invoice, and it was later given to Mr Simonsen in Oslo so that payment could be made. Mr O'Brien denied any such conversation took place with Johansen on December 20th.

Mr Simonsen's evidence was even more damaging to Mr O'Brien. He said that on December 21st or 22nd, 1995, he received a call from Mr O'Brien during which the Irish entrepreneur said he didn't want Mr Austin's name to appear on any invoice sent by Telenor to Digifone in relation to the $50,000.

This, of course, would not make any sense if Mr O'Brien's version of the payment was true. He has denied that any such call could have taken place.

Mr Simonsen said he issued an instruction to the Telenor accounts department that Mr Austin's name not appear on the invoice. The invoice was issued in early January. When Mr Simonsen was shown a copy of the invoice he was told was being faxed to Dublin, he saw that Mr Austin's name was on it. He raced to the fax but it was too late. He immediately phoned Dublin and asked someone there (who has not been identified) to tear up the document coming out of the fax. It was incorrect, he said he told the Digifone employee.

A new invoice was issued for $50,000. Mr O'Brien then called Mr Simonsen again, later in January, Mr Simonsen said, asking that that invoice be cancelled and a new one issued, for Irish pounds rather than dollars. This, according to tribunal counsel Mr Jerry Healy SC, would have had the effect of making it harder to connect the invoice with Telenor's $50,000 payment to Mr Austin. Mr Simonsen said he did as instructed.

Mr O'Brien said no such conversation could have taken place and that he had nothing to do with any of these invoices and knew nothing about them until much later. (The January 1996 dollar invoice was cancelled and a new invoice was issued, in Irish pounds.)

Mr O'Brien's position while in the witness box was very plain. "I am saying that the evidence that we have heard from Telenor is not true," he told Telenor's counsel, Mr Eoghan Fitzsimons SC.

"I want to be very clear. There is no beating about the bush about that." He was, in other words, alleging a conspiracy.

Mr Fitzsimons said the only way Mr Digerud could have signed, on December 20th, 1995, the December 14th, 1995, invoice sent by Mr Austin to Mr Johansen in Oslo, was if the invoice was brought to Dublin by Mr Johansen on December 20th.

"This really blows your evidence out of the water, where Mr Digerud's and Mr Johansen's evidence is concerned on this particular topic," the barrister said. Mr O'Brien did not agree.

Mr Fitzsimons pointed out that the invoice, with the annotation by Mr Digerud, was shown to Mr O'Brien and other Digifone executives in November 1997, when a major internal Digifone inquiry was conducted into the Fine Gael donation.

"How devious are you suggesting that my client's witnesses are?" He asked Mr O'Brien how far back the conspiracy he was alleging against Telenor went. Mr O'Brien said that was a question he would be better addressing to his clients.

On Mr Simonsen's motives for giving what Mr O'Brien said was false testimony, Mr O'Brien suggested it might be because he was a junior executive worried about his future career.

"Mr Simonsen allegedly said that I phoned him and I know that is not the truth," Mr O'Brien said. "And really what I was saying is that if you are an executive in a company, you toe the party line."

Mr Fitzsimons described this as a "terrible remark about this young man". Mr O'Brien said he had had reports of the evidence of the Telenor executives. "My view at the end of it was that somebody is not telling the truth. In this case, its Telenor."

The tribunal chairman, Mr Justice Moriarty, will in time have to rule on the issue.