Forty potential breaches of the ministerial code have never been referred for investigation by the ethics adviser, data shows.
It comes as a parliamentary committee warned historical breaches of the code may never be investigated or resolved, including the conduct of the home secretary or Islamophobia claims against a former chief whip.
Rishi Sunak has launched a hunt for a new adviser on ministerial interests but the Guardian reported last week several candidates have turned down the role. Sunak is not offering any enhanced powers – which means advisers would not be able to launch their own investigations.
The ethics adviser, when appointed, would probably face calls to renew or open at least two complex investigations – including concluding one into alleged Islamophobic comments made by the then chief whip, Mark Spencer, to the Conservative MP Nusrat Ghani.
There will also probably be pressure to open an investigation into the home secretary, Suella Braverman, who was sacked for a potential security breach by Liz Truss though reinstated by Sunak.
In a new report, the public administration and constitutional affairs committee, said it would be concerning if the prime minister’s new adviser was not allowed to examine historical cases. It suggests the inquiry into allegations of racism towards Ghani will not be concluded, which the committee says is “unsatisfactory”.
It recommends that former ministers and civil servants who break the rules regulating the “revolving door” between government and private sector jobs should face legal action, to act as a “sufficient deterrent” for improper conduct.
It said primary legislation should be introduced to establish the independent adviser as a statutory position and they should retain the power to initiate investigations and complete any legacy inquiries they inherit.
The committee’s chair, the Conservative MP William Wragg, said: “Our inquiry has found that although we have a sophisticated landscape of ethics watchdogs in the UK to safeguard standards in public life, they lack the power to enforce the rules. The prime minister is rightly the ultimate arbiter of the rules in our system. We urge him to show leadership and give legal status to all the ethics watchdogs.”
The pressure group Transparency International has been among those calling for the role to have significantly enhanced powers since it was vacated by Christopher Geidt five months ago under Boris Johnson.
In analysis of media reports, the group found 40 potential breaches of the ministerial code have not been investigated over the past five years. Those included:
Meetings by Nadhim Zahawi and Kwasi Kwarteng with the Libyan politician Fathi Bashagha, organised by the lobbyist Mark Fullbrook who became Truss’s chief of staff.
Michael Gove’s acceptance of £120,000 in donations from property developers while serving as housing secretary.
Multiple meetings held by Anne-Marie Trevelyan with a Chinese state-owned nuclear power company with no record of what was discussed.
All the ministers have claimed donations and meetings were recorded accurately, but Transparency International said each one represented a potential breach that should be investigated where a perceived conflict of interest could arise.
The group has also called for appointments to the role to be made with a competitive process and for the position to be defined in law – rather than both being at the whim of the prime minister.
Daniel Bruce, the chief executive of Transparency International UK, said: “This is further evidence the conventions-based system that is supposed to uphold standards in high-office is simply not fit for purpose. The extent of potential misconduct at the heart of government may be a shock to many, but equally concerning should be the lack of transparency over why these cases were never investigated independently.”
Sir Alex Allan, a former independent adviser, resigned after Boris Johnson refused to take action after an investigation into bullying by the then-home secretary Priti Patel.
Truss, during her short tenure as prime minister, expressed no interest in appointing a successor to Geidt. No transparency data on ministers’ interests has been published since May, despite multiple changes of government including three prime ministers.
While Sunak searches for Geidt’s successor, a separate independent investigation has been launched into the conduct of the deputy prime minister, Dominic Raab, by the senior employment barrister Adam Tolley KC, who is examining three bullying complaints.
A government spokesperson said: “We have been clear that this government will have integrity, professionalism and accountability at every level and have committed to appointing an independent adviser on ministerial interests. This process is ongoing.”