Prime Minister Malcolm Turnbull has rebuffed calls for Mal Brough to stand aside while police examine his role in the James Ashby affair, but has left open the possibility if new developments emerge.

Opposition Leader Bill Shorten had earlier called for Mr Brough to stand aside as Special Minister of State until the police investigation is complete.

Mr Brough has previously admitted to encouraging James Ashby, a former aide to Mr Brough's political rival Peter Slipper, to make copies of the former Speaker's diary. These were then leaked to the media in a bid to damage Mr Slipper, who subsequently lost the seat of Fisher to Mr Brough at the 2013 election.

Earlier this month Australian Federal Police raided the homes of Mr Brough and Mr Ashby in connection with their investigation into whether any laws were broken in copying and distributing the diary records of Mr Slipper, a former Commonwealth officer.