The findings of an inquiry into Home Secretary Priti Patel's conduct must be made public "as soon as possible", the Labour Party has said.
PM Boris Johnson asked the Cabinet Office to establish the facts following claims Ms Patel had bullied staff at three different government departments.
Ms Patel, who was interviewed as part of the process, has denied the claims.
It is understood the report has been completed and the outcome is likely to be known in the coming days.
No final decisions have been taken, and the process is officially described as "ongoing", but Whitehall sources have indicated there is not enough evidence to require Ms Patel's resignation.
The Cabinet Office has been contacted for comment.
Its inquiry - in line with the Ministerial Code in standards in public life - is separate to the ongoing employment tribunal claim lodged by ex-Home Office chief Sir Philip Rutnam.
Labour's shadow home secretary, Nick Thomas-Symonds and Rachel Reeves, shadow Chancellor of the Duchy of Lancaster, have called on Cabinet Office minister Michael Gove to update Parliament about the progress of the inquiry.
In a letter sent to Mr Gove last week, seen by BBC News, they wrote: "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.
"As a result we are calling on you to ensure that the findings of the inquiry are published as soon as possible."
Labour says it has received no reply to the letter.
Commenting on press reports that Ms Patel has been cleared, Dave Penman, general secretary of the First Division Association, which represents senior civil servants, said complaints "of this nature" needed an "independent investigation" that was "free from political influence".
He added: "It tells you everything that is wrong with investigations under the Ministerial Code that a process which is not written down, which contains no rights for those who might complain, that is determined in secret, alone by a prime minister who has already pledged his allegiance to the minister in advance, and which allows no right to transparency or challenge for anyone who complained, would then be leaked on the evening before the home secretary is due to appear before the Home Affairs Select Committee."
The investigation was launched by Cabinet Secretary Sir Mark Sedwill and the report is being compiled by senior Cabinet Office official Helen McNamara and senior civil servant Alexander Allan.
Ms Patel was questioned by MPs about how her department has handled the coronavirus outbreak during a virtual hearing of the Home Affairs Select Committee on Wednesday.
She said the decision not to test or isolate people arriving in the UK was based on advice from the Scientific Advisory Group for Emergencies (Sage) and said the impact of thermal screening would have been "negligible".
Ms Patel's last appearance before the committee was on 23 October.
Earlier this month, Ms Patel was accused of avoiding scrutiny during a time of national emergency.
Committee chair Yvette Cooper wrote six letters to the home secretary over the last three months in an effort to set a date for her to give evidence as other ministers have done.
After not replying to several of the letters and declining invitations to attend on earlier dates, Ms Patel responded by saying she was "disappointed at the increasingly adversarial tone of our exchanges".
In a letter confirming her 29 April appearance, Ms Patel said she was "committed to ensuring the Home Office is better open to scrutiny and transparency" and highlighted that she had offered "regular briefings" to the committee.