The inquiry into allegations that Home Secretary Priti Patel bullied officials must be made public “as soon as possible”, Labour has demanded.

A Cabinet Office investigation was launched over claims that she belittled colleagues and clashed with senior officials in three different departments.

There has been no official comment on whether the inquiry has concluded, but multiple reports say she has been cleared of breaching the ministerial code.

Cabinet Office minister Michael Gove was written to by his opposite number at Labour, Rachel Reeves, and shadow home secretary Nick Thomas-Symonds, calling for transparency.

“At a time when additional powers are being assumed by the Government, the imperative that the public are completely assured of the conduct of senior ministers is even greater,” they wrote.

“As a result, we are calling on you to ensure that the findings of the inquiry are published as soon as possible. Parliament should also be updated this week about the progress of the inquiry and the timing of its completion.”

Labour said the letter was sent last week and that no response has been received.

The Prime Minister’s official spokesman said the process was still “ongoing” and the report had not been completed.

Ms Patel will still face legal action by the former top civil servant in her department, Sir Philip Rutnam, who is claiming “constructive dismissal” at an employment tribunal.

Sir Philip, who was the Home Office’s permanent secretary, quit earlier this year accusing Ms Patel of a “vicious and orchestrated briefing campaign” against him.

Ms Patel expressed concern at the “false” claims and allies described her as a “demanding” boss but not a bully.

Dave Penman, who is supporting Sir Philip as general secretary of the FDA civil servants’ union, raised his concerns over reports that the Cabinet Office investigation had quietly concluded.

He said it was “suspicious” that the news surfaced shortly before her appearance before the Commons Home Affairs Committee on Wednesday morning, where she will be questioned about her department’s response to the coronavirus outbreak.

Mr Penman told the PA news agency: “The ministerial code was never really intended to deal with these sorts of issues like bullying and harassment, it was for things like conflicts of interest from ministers.

“It doesn’t equate to any normal bullying and harassment process any significant employer would have or would apply to anyone else in the civil service.

“The whole process is a relic from a bygone age and what we need is an independent and transparent process where ministers can be held to account for their behaviour or exonerated quickly and publicly if there’s nothing there.”