Boris Johnson failed to disclose that he met a uranium lobbyist while prime minister before entering into a new business with a controversial Iranian-Canadian uranium entrepreneur, the Observer can reveal.

Johnson’s new company Better Earth Limited also employs Charlotte Owen, a junior aide with just a few years work experience whom he elevated to the House of Lords last year at the age of 29, sparking intense controversy.

Transparency campaigners say there appear to be “serious public interest questions to be answered” over the nature and timeline of Johnson’s relationship with his co-director, Amir Adnani, the founder, president and CEO of Uranium Energy Corp, a US-based mining and exploration company, championed by former Trump adviser Steve Bannon.

Amir Adnani, a Canadian citizen who is the director of a network of offshore companies based in the British Virgin Islands, incorporated Better Earth in December last year. On 1 May, Companies House filings reveal, “The Rt Hon Alexander Boris de Pfeffel Johnson” was added as a director and co-chairman. And this summer, Charlotte Owen – now Baroness Owen of Alderley Edge – joined the company to work alongside him as its vice-president.

The Advisory Committee on Business Appointments (Acoba), which oversees ex-ministerial appointments, explicitly warned Johnson in April 2024 that the “broad overlap” between his roles in office and at Better Earth may entail “unknown risks” because of the lack of transparency over the firm’s clients. A statement from the Cabinet Office noted the potential for a conflict of interests particularly because of “the unknown nature of Better Earth’s clients – specifically that there is a risk of a client engaging in lobbying the UK government.” The committee also told the former prime minister it feared “that you could offer Better Earth unfair access and influence across government”.

Acoba was reassured that Johnson “did not meet with, nor did you make any decisions specific to Better Earth during your time in office”. But the Observer can reveal that Johnson met Scott Melbye, the executive vice-president of Uranium Energy Corp – Adnani’s company – in the House of Commons in May 2022 when he was still prime minister.

Adnani’s social media post about the event claimed that Melbye and Johnson spoke about “nuclear power and uranium”.

Neither Johnson or Adnani have responded to press inquiries about this encounter or when they first met. The encounter was not recorded in the prime minister’s official diary.

Uranium is the raw ingredient for the enriched uranium needed to fuel nuclear reactors. Just days before leaving office, Johnson announced a £700m investment in the controversial Sizewell C reactor stating the country needed to “Go nuclear, go large!”. At the time, Caroline Lucas, the then Green MP and former party leader, described Sizewell C as “massively costly, achingly slow and carries huge unnecessary risks”.

Among those who cheered the Sizewell C investment was Adnani. He excitedly posted the announcement on his Twitter account: “Boris Johnson plans to sign off on new £30bn nuclear plant in his final week in power! #uranium.”

Adnani has appeared at least twice on former Donald Trump adviser Steve Bannon’s War Room podcast, and on one occasion told him that his ambition was to achieve “full spectrum energy dominance”.

Headquartered in a serviced office building in Sevenoaks, Better Earth describes itself as an “energy transition company”. Its website, which is currently under construction, says it will “work directly with national governments and regions that are seeking both inward investment and/or to reduce their emissions ahead of 2030”.

The apparent lack of transparency extends beyond the nature of the firm’s clients: the company no longer has a person of significant control registered at Companies House. The initial filing states that its single share is owned by another company called “Emissions Reduction Corp” registered in Carson City, Nevada.

US company searches reveal the firm was previously called Carbon Royalty Corporation, a Delaware-based company whose directors include Adnani and Nicole Shanahan, who was until recently Robert F Kennedy Jr’s running mate in his campaign for US president before he endorsed Trump. Delaware is a “dark” jurisdiction but sources suggest Carbon Royalty Corporation has raised $40m since it was incorporated in 2021 and its investors appear “undisclosed”, although this is not illegal.

Baroness Margaret Hodge, the former Labour MP who led parliament’s Public Accounts Committee from 2010-2015 said there were “at least four very serious public interest questions” to be answered about the appointment.

“What on earth is an ex-prime minister of the United Kingdom doing, working for a company with an opaque structure? In my experience those who choose to have a UK company owned by a foreign entity only do that because they may have something to hide. What is it in this case? Given the sensitivities around nuclear capabilities we should know who he is in business with, where the money is coming from and why he is using a financial structure that appears to hide the beneficial ownership of the company.”

Better Earth, Amir Adnani and Boris Johnson declined to respond to the Observer’s inquiries about Better Earth’s line of work, funding or any other matters.

The appointment also raises further question marks over Johnson’s relationship with Baroness Owen, a previously unknown junior political adviser who had worked for a matter of months with Johnson at Number 10. Her appointment to the Lords, where she took the title Baroness Owen of Alderley Edge in July last year, became the subject of intense speculation. With just a few years’ job experience under her belt, she now holds the position for life. In her maiden speech in November last year, she thanked Johnson for “putting a great deal of trust in me”.

That trust has now been extended to a senior role in his new company, Better Earth, though her role has also not been widely publicised. She recently updated her House of Lords page to note that she has a paid position as “Vice President, Better Earth Limited (energy transition company)” though she does not appear on the company’s website, X feed or LinkedIn page.

Owen mentioned climate only briefly in her maiden speech earlier this year, preferring to showcase her interest in technology, and has no previous employment experience in environmental, nuclear, or green issues. She declined to answer any of the Observer’s questions about her role.

Owen joins two other former Conservative ministers at the firm: Chris Skidmore, who resigned the whip and the party over Rishi Sunak’s oil and gas plan, is Better Earth’s COO, while Nigel Adams, a Johnson ally and former minister without portfolio, is CEO. There is no suggestion that either Skidmore or Adams were in breach of transparency rules.

Before Johnson became a director of Better Earth in May this year, he wrote to Acoba, the government watchdog, alerting them to the appointment. This came during the same period Acoba had accused him of refusing to answer its questions about whom he’d met as a consultant on behalf of a hedge fund, Merlyn Advisors, during a trip to Venezuela.

The incident led the committee’s chairman, Eric Pickles, to warn that Johnson’s behaviour had proved its rules were “unenforceable”.