Lord Mandelson did discuss European Union trade issues with Oleg Deripaska, the Russian oligarch, despite his denials that they had ever talked about the subject.

The business secretary, who at the time was the EU’s trade commissioner, wanted to know whether Deripaska supported or opposed tariffs on Russian timber exports to Europe.

Mandelson has said he never discussed EU matters with Deripaska. However, a source close to Deripaska said they had discussed wood tariffs, the subject of EU talks with Russian officials.

Last week, in a statement to The Sunday Times, Peter Power, Mandelson’s spokesman, confirmed that Mandelson had discussed timber tariffs with Deripaska but said they had never talked about aluminium tariffs.

He said Mandelson’s claim that he had “never” discussed EU matters with Deripaska related only to the time he was on Corfu.

The timber duties were the subject of talks between the EU and Russia, and Deripaska’s views were important because he controls one of his country’s biggest wood processing and lumber companies.

Mandelson has faced questions over his links to Deripaska, 40, since it was revealed he was a guest on the Russian tycoon’s yacht, the Queen K, in the summer.

In an interview on the Today programme on BBC Radio 4 on Tuesday, Mandelson insisted that any scrutiny of his links to Deripaska should focus on “what happened in the conversations” between the two men.

He said: “In these conversations with this gentleman there was no discussion of EU trade business; there was no discussion about tariffs or antidumping duties.” After the story broke about Mandelson’s links to Deripaska, Power said the business secretary had “never had a discussion with Mr Deripaska, or anyone else from his company, about aluminium duties or any other matter relating to the EU”.

The issue of tariffs levied by Russia to discourage other countries from importing its timber has been one of the main stumbling blocks to the country’s attempt to join the World Trade Organisation.

Although Deripaska’s fortune was amassed in the aluminium industry, Continental Management, a subsidiary of Basic Element, his holding company, is one of the leading firms in the Russian wood industry, employing 13,000 workers.

Deripaska is said to have told Mandelson that the duties were justified to protect Russia’s wood processing businesses.

Mandelson, a firm believer in free trade, wanted the tariffs removed. He remained resolute in opposing the duties after consulting Deripaska.

The business secretary maintains there was no possible conflict of interest in his relationship with Deripaska and has previously declined to provide details of their meetings.

George Osborne, the shadow chancellor, who discussed a possible Conservative party donation with Deripaska, has provided a more detailed account of his meetings.

Power admitted last week that there was a “long discussion” between Mandelson and Deripaska about timber tariffs, with Mandelson arguing they should be scrapped and the Russian insisting they should be kept. Power said the duties were still in place and Russia was “no further along the road” to membership of the World Trade Organisation.

A spokesman for Deripaska said the tycoon would not comment on private meetings or conversations.

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