The nation's most senior border protection official earned hundreds of thousands of dollars while on leave pending a labyrinthine, months-long set of inquiries into whether he abused his power, two Senate hearings have revealed.

The head of the Prime Minister's Department, Martin Parkinson, took about four months to finish a report for the government on whether the head of the Australian Border Force, Roman Quaedvlieg, should be fired.

Dr Parkinson was acting on an investigation that had already been carried out by the corruption watchdog, the Australian Commission for Law Enforcement Integrity.

Attorney-General Christian Porter, in whose hands Mr Quaedvlieg's fate now rests, confirmed that Prime Minister Malcolm Turnbull had asked him to consider the report rather than Home Affairs Minister Peter Dutton to "prevent any apprehension of bias given Mr Quaedvlieg’s reporting obligations to Minister Dutton".

Mr Quaedvlieg has been accused of abusing his power by helping his girlfriend - an ABF employee - get a job at Sydney Airport. He has himself expressed frustration at the delays, during which he has been on full pay on his $618,000 annual salary since late May.