The former EU trade commissioner is leading a British delegation in the Russian capital on a four-day visit aimed at rebuilding trade ties that have been damaged over a series of diplomatic disputes.
When asked by RIA Novosti about the 'scandal' over his trips on Oleg Deripaska's yacht, Mandelson said: "You didn't see a huge scandal, you saw huge stories, which is not the same thing."
"Yes I have visited Mr. Deripaska on his yacht, and during my visit to him, the European Commission has confirmed there was no conflict of interest, no impropriety - he didn't offer me any favors and I didn't offer him any favors. And that's where the story should end. But of course I'm not surprised that people want to push the story further, because this is what excites many journalists."
"I might add that most of my conversation time with Mr. Deripaska has been taken up with a disagreement between us over Russia's accession to the WTO. No doubt we will continue to have that disagreement."
When asked to give further details of his relationship with the oligarch, he said: "I've answered you sufficiently, I think."
Britain's opposition Conservative Party has suggested that Mandelson may have used his position as EU trade commissioner to secure an aluminum tariff reduction that benefitted Deripaska.
The Conservatives have come under pressure over accusations that the shadow chancellor and the party's chief fundraiser had also been guests on Deripaska's yacht, and had solicited an illegal donation.
The billionaire has refused to comment on the various allegations. A spokesman told British media on Monday: "As he has demonstrated throughout this, Mr. Deripaksa has no intention of commenting on private meetings and private conversations."
