A report into allegations Home Secretary Priti Patel bullied staff should be made public, the prime minister's adviser on standards in public life has said.
Former MI5 chief Lord Evans warned that unresolved inquiries into ministers' conduct undermined public trust.
A Cabinet Office investigation into allegations about Ms Patel's behaviour was launched in March.
She has always strongly denied claims that she bullied staff.
In February Sir Philip Rutnam, the top civil servant in the Home Office, resigned saying he had been the target of a "vicious and orchestrated briefing campaign". He is pursuing an employment tribunal claim.
The Committee on Standards in Public Life advises the prime minister on ethical standards across public life in England and is chaired by ex-MI5 boss Lord Evans of Weardale.
He told the BBC he was not in a position to judge the accuracy of the complaints about the home secretary but said the public needed to know that allegations are "properly and independently investigated".
"We want to make sure the system we have in place can resolve those issues so that people can have confidence the standards are being upheld in the right places and by everybody involved," he told Radio 4's The World at One.
Asked specifically about Ms Patel's case he said there may be "good reasons" why some findings are not published but argued that any causes for delay should be explained.
"I think because they are left hanging in the air people are worried about it and that tends to reduce people's trust."
He also said that the process of investigating ministers should be more independent and transparent - and he suggested taking the responsibility for triggering such inquiries away from the prime minister.
In an interview with the Times, he said because the report on Ms Patel had not been published "it is very difficult to know whether there was something here or whether there wasn't".
Responding to Lord Evans' comments, Labour's shadow home secretary Nick Thomas-Symonds said: "It is a disgrace that the report into allegations of bullying against the home secretary is being suppressed.
"Continuing to refuse to release the report not only makes clear that the Tories have something to hide, it also undermines trust in politics at a crucial time - the report must be published without further delay."
A government spokesperson said: "The process is ongoing and the prime minister will make any decision on the matter public once the process has concluded."