Labour leader Pat Rabbitte has said he followed party procedures in relation to a political donation he received from lobbyist Frank Dunlop in November 1992 but then returned three weeks later.
He again denied claims by Mr Dunlop that the pair discussed rezoning when the lobbyist visited the politician's house to make the donation.
"I was offered a donation," Mr Rabbitte said yesterday . "I sent it back by cheque, it was cashed. And as far as I'm concerned, I'll deal with it at the tribunal."
During an interview on This Week on RTÉ Radio One, Mr Rabbitte said he was "completely taken by surprise" by the donation.
"I didn't know of course until I opened the envelope whether it was two hundred or two thousand." He said he followed the procedure in the constituency organisation of Democratic Left and considered the donation along with other solicited and unsolicited monies gathered during the campaign. "In this case, as the donor agrees, this donation was not solicited and I resolved to recommend that they send it back and they agreed and we did that by cheque."
The Mahon tribunal is investigating the rezoning of lands in Ballycullen near Tallaght, and a series of payments and donations made by Mr Dunlop to politicians, some of which he has claimed were bribes.
Mr Rabbitte supported the Ballycullen rezoning a number of weeks before Mr Dunlop made the donation. The lobbyist has specifically stated that the money was a donation, but has claimed it was for £3,000 as opposed to the £2,000 stated by Mr Rabbitte.
He also rejected suggestions there was any "great mystery" in the three weeks it took him to return the money, or that he should receive political donations.
"I don't think it was strange at all in the context of the time. The fact of the matter is that general elections were financed by donations. What was surprising about this was that I should have got a donation or been offered a donation from somebody prominent in another political party."
Mr Rabbitte also said he was concerned about RTÉ's promotion of yesterday's interview.
He said he had been asked for what he thought would be a discussion about public affairs, focusing on recent remarks by Taoiseach Bertie Ahern about a potential coalition between Fianna Fáil and Fine Gael. Instead he woke up yesterday morning "to a promo for the programme to the effect I am coming on to reply to Mr Dunlop's claims.
"From the point of view of the tribunal that promo implies disrespect on my part for the tribunal. And I want to say that, although I was very surprised at the lack of rigour last week in testing Mr Dunlop's credibility and consistency, that by appearing on this programme I intended no disrespect to the tribunal. I took it as another ordinary interview, and I just want to make it clear."
Mr Rabbitte also dismissed recent comments by Mr Ahern suggesting that Labour and Fianna Fáil could form the next coalition government.
He said both Fianna Fáil and the Progressive Democrats had been "casting around for potential partners.
"The least that you could say in that is that it confirms the lack of confidence on the part of the two parties that they can be returned to Government again."