A report into allegations that Home Secretary Priti Patel bullied staff has concluded she broke the ministerial code, sources have told Sky News.
It is due to be published imminently but is understood to be being held up by a row over whether the senior cabinet minister will apologise.
The inquiry was launched nine months ago but its conclusions have not yet been released despite being completed some time ago.
The report is said to be critical of Ms Patel’s behaviour and will reportedly call for her to make a formal apology after finding that she broke the code governing ministers’ conduct by failing to treat staff with consideration and respect.
However, Boris Johnson and Home Office officials are understood to be unable to agree a timetable to publish the conclusions because of a disagreement about the apology.
Earlier, the Financial Times reported that the prime minister intended to “fudge” the outcome of the report and not demand Ms Patel leave her post.
Labour claimed the news had “all the hallmarks of a cover up”.
Shadow home secretary Nick Thomas-Symonds MP said: “These revelations could not be more serious. This has all the hallmarks of a cover up from the prime minister and raises fundamental questions about his judgement.
“His actions are all but condoning bullying in the workplace.
“In any other area of life this would not be acceptable. Yet again, it seems to be one rule for them and another for everyone else.
“The report needs to be published in full immediately and both the prime minister and home secretary must come before parliament to answer questions on this mess.”
Mr Thomas-Symonds has written to the standards watchdog, urging it to investigate and saying Labour has lost faith in the government’s ability to handle the issue.