Former prime minister Malcolm Turnbull has warned of the appearance of "political influence" in the police investigation into Energy Minister Angus Taylor in a rebuke to the government over its handling of the affair.

In a direct criticism of Prime Minister Scott Morrison, the former leader said he would not have telephoned NSW Police Commissioner Mike Fuller over the investigation because of the risk it would be seen as interference.

Former prime minister Malcolm Turnbull has criticised Prime Minister Scott Morrison for calling NSW Police Commissioner Mick Fuller over the police investigation into Energy Minister Angus Taylor. Credit:Janie Barrett, Alex Ellinghausen

"It is always critically important in any police inquiry, particularly something that involves a politician, that the police are, and are seen to be, acting entirely free of political influence," Mr Turnbull told Sky News on Wednesday morning.

"Now, I'm sure the call the Prime Minister made to the NSW Police Commissioner was innocuous but it would have been much better had it not been made. Because it is vitally important that that inquiry, that is being conducted by the NSW Police, like every inquiry they undertake, is seen to be conducted entirely free of political influence.