Adam Werritty personally arranged a meeting between Liam Fox and a senior Iranian lobbyist with close links to President Mahmoud Ahmadinejad's regime, the Guardian has learned.

The Iranian lobbyist visited Fox in May 2009 at Portcullis House. Werritty met him at the entrance of the parliamentary building and escorted him up to Fox's office, sitting in for half a meeting on Iran. "I thought Werritty's was Fox's assistant," the lobbyist – who declined to be named – told the Guardian. "Werritty was the main contact for meeting Fox. He was the person who arranged the time of the meeting. He collected me at the gate of Portcullis House and took me up to Fox's office.

"There was a meeting between the three of us. Werritty wasn't introduced to me. I didn't get the impression that Werritty was an especial expert on Iran. I didn't know who he was but thought he was either an official or Fox's assistant."

The lobbyist declined to reveal what was discussed. He described Werritty as "a very pleasant, sociable guy". He said he met Fox briefly twice after he became defence secretary, with others present.

The revelation is nevertheless likely to add to claims not only that Werritty masqueraded as Fox's international fixer but that he was running a shadow foreign policy on Iran – a policy more hawkish than the official government position. David Cameron is said to have been annoyed by some of Fox's more neo-con pronouncements on the subject.

In February, Werritty and Fox flew to Israel for a high-profile strategic conference on regional security. Fox called for stronger sanctions to compel Iran to give up its nuclear weapons programme. He warned the Commons during the same period that it was "entirely possible" Iran could have a nuclear weapon by 2012.

Werritty also arranged and attended a dinner at the conference with Fox and Matthew Gould, Britain's ambassador to Israel. Other top political figures also attended. The Independent reported that senior Israeli diplomats were under the impression that Werritty was an official adviser to the defence secretary. It is not clear why Werritty, rather than Foreign Office officials, organised the dinner.

Werritty attended the same conference in February 2009 as an "expert" on Iran. He was a guest of a UK-based pro-Israeli lobbying organisation. The British Israel Communications and Research Centre (Bicom) paid for his flight and hotel bill.

Lorna Fitzsimmons, Bicom's chief executive, said: "We have only ever done two things with Adam Werritty in the five years I have been at Bicom. We funded him to go to the Herzliya conference in 2009 to talk on a panel on Iran and I accepted an invitation from him to talk to a panel on Iran at an event in London in 2009 or 2010."

It's unclear, however, how deep Werritty's Iranian connections are, and on what basis he is a specialist on the region. Richard Dalton, Britain's ambassador in Tehran between 2003-2006, said: he had not come across Werritty, either during his time in Iran and subsequently. "He hasn't broken the surface of Iran expert circles. I've never read anything written [on Iran] by him."

One Iranian exile said that he had met Werritty in London to discuss Iranian politics. "We met over coffee several times", he said. "He [Werritty] even spoke a few words of Persian," the exile recalled. A second Iranian exile added that Werritty was a regular participant at seminars on Iran held by Chatham House, the foreign affairs thinktank, and the Royal United Services Institute.

The source said that Werritty had visited Iran once back in 1997 and the Iranian chamber of commerce. He said that when he met Werritty in 2005-2006 he described himself as "someone very close to Liam Fox".

The source added: "I heard recently from Arab colleagues that Werritty had called himself an adviser to Fox. I didn't get the impression he was an Iran expert. He could talk convincingly but I didn't see any depth in his Iran information."

It is understood that Bicom paid less than £1,000 for Werritty to fly to Israel to attend the 2009 conference, an annual event organised by academics and former luminaries of the country's intelligence and security establishment to discuss strategic and Middle Eastern issues and promote Israel's view of them.

Werritty was invited to attend by one of its organisers, Tommy Steiner, a Nato and international relations expert who served as the executive director of the Atlantic Forum of Israel, a network-based policy organization that promoted "Israel's relations with the Euro-Atlantic Community". Steiner was unavailable for comment.

Werrity is described in the list of 2009 Herzliya participants as "Dr Adam Werritty, Advisor, Office of Shadow Defense Secretary; UK Executive Director, The Atlantic Bridge" but is not listed as speaking on Iran or anything else. He does not appear in the list of 2011 participants.

In his speech in February Fox spoke of the need to resolve the Palestinian issue as way of undercutting Iran's ability to cause trouble in the Middle East. The 2009 conference was held just weeks after the end of Israel's Operation Cast Lead in the Gaza Strip, in which 1,400 Palestinians were killed.