One of the Federal Government's most highly paid public servants could be dismissed or resign within weeks after two separate misconduct investigations.

Key points: Roman Quaedvlieg has earned more than $500k since taking leave amid an investigation last May

Roman Quaedvlieg has earned more than $500k since taking leave amid an investigation last May Attorney-General Christian Porter will make final decision on whether he should be dismissed

Attorney-General Christian Porter will make final decision on whether he should be dismissed ABC understands once a decision is made and Governor-General has signed off, Home Affairs Minister Peter Dutton would need to notify Parliament

Government sources have confirmed that one of the reviews has recommended Border Force Commissioner Roman Quaedvlieg should be sacked.

Mr Quaedvlieg has earned more than $500,000 since taking leave in May last year when his alleged misconduct was investigated.

The commissioner's alleged relationship with a former staffer has been examined by the Australian Commission for Law Enforcement Integrity.

Secretary of the Department of the Prime Minister and Cabinet Martin Parkinson has also completed a review into Mr Quaedvlieg's alleged misconduct.

That review has been sitting on Attorney-General Christian Porter's desk since February and he will make the final decision on whether the Commissioner should be dismissed.

While Mr Quaedvlieg sits within Home Affairs Minister Peter Dutton's portfolio, Mr Porter has been asked to make the final decision to avoid any appearance of bias.

"This is to prevent any apprehension of bias given Mr Quaedvlieg's reporting obligations to Minister Dutton under the Australian Border Force," Mr Porter said.

"As a result of this request, and before receiving Dr Parkinson's report, I sought legal advice from the Australian Government Solicitor to satisfy myself that I can consider and determine this matter."

The ABC understands that once a decision has been made and the Governor-General has signed off, the Home Affairs Minister would need to notify Parliament.

Mr Quaedvlieg has been contacted for comment. He has previously denied any wrongdoing.

He is understood to be deeply frustrated by the duration of the investigation, as is the Federal Opposition, which has demanded answers over the drawn-out process.