Revealed: Fox's best man and his ties to Iran's opposition

An IoS Investigation: The murky world of Adam Werritty: Self-styled adviser 'had links to Mossad'.

Adam Werritty, the man at the centre of the Liam Fox cash-for-access scandal, has been involved in an audacious plot to topple Iranian President Mahmoud Ahmadinejad, it was claimed last night.

The self-styled adviser to Mr Fox, whose close personal friendship with the former defence secretary led to Mr Fox's downfall, has visited Iran on several occasions and met Iranian opposition groups in Washington and London over the past few years, The Independent on Sunday has learnt.

Mr Werritty, 33, has been debriefed by MI6 about his travels and is so highly regarded by the Israeli intelligence service Mossad – who thought he was Mr Fox's chief of staff – that he was able to arrange meetings at the highest levels of the Israeli government, multiple sources have told The IoS.

Mr Fox resigned on Friday after a stream of revelations surrounding his dealings with his adviser, centring on 18 meetings abroad at which Mr Werritty was present, including in Dubai, Sri Lanka and Israel, and 22 at the Ministry of Defence. After vowing to fight the disclosures a week ago, Mr Fox quit the Cabinet on Friday when details emerged of the business and intelligence interests of Mr Werritty's financial backers.

The minister admitted that he had allowed the distinction between his personal interests and government activities had become "blurred". But The IoS has learnt that Mr Werritty's travels went further than the luxury hotels of Colombo and Dubai: he has used his House of Commons-branded business card, which said he was Mr Fox's adviser, to pursue his business interests in conflict-torn South Sudan, other developing African countries and Iraq. The aide has also held talks in London with representatives of the new Libyan government in recent weeks. It is not known whether Mr Fox was present.

The fresh disclosures are likely to form part of Sir Gus O'Donnell's inquiry into Mr Fox and Mr Werritty, which was launched last week as the scandal unfolded. The revelation that the man who had unrestricted access to Mr Fox while he was serving in David Cameron's Cabinet was at the same time attempting to unseat the Iranian President will fuel alarm in the Foreign Office that he was pursuing a freelance foreign policy and acting as a "rogue operator".

At the height of the storm surrounding Mr Fox last week, "friends" of the MP tried to distance him from Mr Werritty by describing him as a "Walter Mitty" figure, to the fury of Mr Fox.

Yet the access to senior government figures Mr Werritty enjoyed across the globe suggests otherwise. Mr Werritty, said one source, worked closely with US-backed neocons who thought they could "bring down Ahmadinejad".

Even though such a plot would be highly ambitious, if not impossible, Mr Werritty's activities fly in the face of the British Government's efforts to pursue a diplomatic solution, through the UN, to Iran's nuclear ambitions.

Mr Werritty joined Mr Fox, while he was shadow defence secretary, on a visit to Iran in the summer of 2007. The IoS understands the adviser has also visited the country on several occasions before and after, although it is not known how long he stayed or whom he met.

Mr Fox is an enthusiastic Atlanticist and is sympathetic to the neocon movement in the United States, which takes a hawkish stance on Iran's nuclear ambitions, although on his 2007 visit to the country he said he hoped for a "diplomatic solution" to the issue. An associate said that Mr Werritty, who can speak some Farsi, would act as a "facilitator" and "take messages" between various opposition figures, although the source insisted he was not a "freelance spy". One diplomatic source suggested that Mr Werritty, once back in London, had been debriefed by MI6 about his travels to Iran. It is not known whether Mr Fox knew the full extent of Mr Werritty's activities, or whether he was merely allowed to continue, and provide information to the British Government on an unofficial basis.

This newspaper has made repeated attempts to contact Mr Werritty but has received no response.

One Whitehall source was scathing of Mr Werritty. The source said: "Ask yourself what he was doing there. It's regime change but only in his own mind. I can't think of anything more stupid, wandering round Iran flying the British flag. Does he really think the answer to Iran's nuclear ambitions – which we all want to resolve – is to have a bunch of people encouraging the opposition there in that way? We do have a responsibility to those people, and anything that's done like that has to have government approval, which he doesn't seem to have had. It's ridiculous. You are inviting people to believe you have the Government's resources behind them, and in fact the opposition is likely to be brutally crushed.

"That is not to say that if he came back to London and he offered to tell MI6 what he had seen while he was in Iran, they wouldn't say 'yes please'. But them picking up as much information as they can, and deniably, is quite different from him being licensed by them."

The IoS has learnt that one senior military figure in a developing country, which this newspaper is not naming to protect his identity, feels he was taken in by Mr Werritty. Last night Labour MP John Mann called on Scotland Yard to launch a fraud inquiry into Mr Werritty and his use of a business card falsely giving his position as an adviser to the former Defence Secretary.

In May 2009, Mr Werritty arranged a meeting in Portcullis House between Mr Fox and an Iranian lobbyist with close links to President Ahmadinejad's regime. In February this year, Mr Werritty arranged a dinner with Mr Fox, Britain's ambassador to Israel, Matthew Gould, and senior political figures – understood to include Israeli intelligence agents – during an Israeli security conference in Herzliya, during which sanctions against Iran were discussed. Despite Mr Werritty having no official MoD capacity, an Israeli source said there was "no question" that Mr Werritty was regarded as anyone other than Mr Fox's chief of staff who was able to fix meetings at the highest levels, and was seen as an "expert on Iran".

The Foreign Office declined last night to comment on any aspect of Mr Werritty's activities .