A billionaire accused in parliament of having links to Moscow intelligence has said that he is not a spy, does not speak Russian and is the victim of a sustained and mysterious campaign of “innuendo.”

In an interview with the Guardian, the New Zealand-born Christopher Chandler shrugged off the claims made last week by a group of cross-party MPs, who cited documents which suspected him of “working for Russian intelligence services”.

The claims were made under parliamentary privilege. They were based on files written by Monaco’s security services, including information from France’s DST foreign intelligence agency. Chandler is described as an “object of interest” to the DST because of his alleged Kremlin ties.

“The documents indicated a link – a noted individual in this country – with Russian intelligence,” the Conservative MP Bob Seely said.

Chandler dismissed the claim: “No, I’m not a Russian spy. I don’t speak Russian. I don’t know anybody in the Russian state thing.”

He said he was baffled by the documents and had no idea he had been under surveillance. The French never contacted him, he said, and their operation went nowhere. “We lived peacefully in Monaco for 20 years. The whole thing is insane.”

Chandler funds the Legatum Institute, a London-based thinktank which has been accused of advocating for a hard Brexit. The Labour MP Ben Bradshaw, who has raised questions about the Kremlin’s possible role in the EU referendum, has called on the authorities to investigate. Legatum said it was an “absurd accusation to say that they had an undue influence on Brexit”.

A series of exposés by the Mail on Sunday claimed that the institute’s former economics director, Shankar Singham, held clandestine meetings with Michael Gove and Boris Johnson. The goal was to pile pressure on Theresa May to leave the single market and customs union.

Chandler, who lives in Dubai and received Maltese citizenship in 2015, insisted that Legatum did not have a firm stance on Brexit. Its focus was prosperity, he said. “Brexit is not our game,” he insisted.

He added that he knew of Nigel Farage but was only dimly aware of Arron Banks, the main financial backer of Leave.EU, which was fined last week by the electoral commission for multiple breaches of expenditure guidelines.

Asked if Russia had sought to influence the outcome of the referendum by backing leave, possibly through undercover methods, Chandler said: “I’m totally unqualified to comment. Is Russia capable of doing that? No question. Did they actually do it? I don’t know. They certainly didn’t do it through us.”

He was reluctant to offer an opinion on whether the Kremlin was trying to sabotage or undermine western democracy. Nor would he say if it had sought to help Donald Trump win the 2016 US election – the consensus view of all US intelligence agencies.

Chandler described the recent attempted murder in England of the former Russian spy Sergei Skripal as “abhorrent”. “Probably it’s what it looks like,” he said when asked who he thought was to blame, but stressed that he was “unqualified” to judge if Moscow was ultimately behind the nerve agent operation.

The businessman was already rich when he invested in Russia soon after the end of the USSR. He said he earned “hundreds of millions” from his stakes in various companies, but also invested “hundreds of millions” and lost large sums in 1998 when the Russian economy collapsed.

Asked if he was the beneficiary of a corrupt system in the 1990s, which created the oligarchs but made most ordinary Russians considerably poorer, Chandler said: “We genuinely believed we could be a force for good [in Russia] by bringing our investment experience.”

Chandler and his brother Richard ended up with a 4% stake in the energy company Gazprom. He said that as a minority shareholder in Russia, he came up against “well entrenched interests”. They placed damaging “kompromat” about him in the Russian media. Some of it may have reached Monaco, he suggested.

The Mail on Sunday reported over the weekend that the Chandlers backed Vladimir Putin’s attempt to oust Gazprom’s chief executive and to replace him with a St Petersburg ally, Alexey Miller. The paper cited a recent pamphlet written by Richard Chandler.

It said the Chandlers managed to appoint their own candidate to Gazprom’s board of directors and then “appealed directly” to the president, paving the way for Miller’s appointment. Chandler acknowledged corruption at Gazprom but said he had fought against it.

He described his brother’s version of events as wrong and said he had not heard of Miller when he got the top Gazprom job in 2001.

Chandler said he never met Putin and met Miller just once, in the summer of 2003. “I didn’t spend enough time to get the measure of him,” he said. Chandler said he offered ideas via an interpreter on how Gazprom might be reformed.

In 2006 Chandler exited from the Russian market when he separated his business affairs from those of his brother. Richard Chandler continued to trade Gazprom stocks. The French and Monaco intelligence files stretch to 85 pages, it is understood.

The businessman visits the UK rarely and does not often given interviews. He has been described as secretive. “I don’t have any secrets. I’m a regular person who likes his privacy,” Christopher Chandler told the Guardian, speaking from Legatum’s townhouse office in Mayfair.

Chandler said he felt aggrieved the MPs had not contacted him before making their “erroneous” claims in the House of Commons. He said he spent several hours last week sitting in Portcullis House, where MPs have their offices, trying unsuccessfully to meet them and to make his case in person.

Lawyers for Chandler have written to several parliamentary committees asking them not to publish the Monaco “dossier”. To do so, they argue, would infringe the businessman’s rights.

And what about Brexit? Chandler is unwilling to say whether it’s a good idea. Or a bad one. “I think it’s up to the UK to determine,” he said. “It will be determined by what you do with it. You can make a success or a failure out of it.”