Former anti-corruption commissioner and senior judge David Ipp says Scott Morrison’s phone call to the New South Wales police chief appears to be an inappropriate attempt to use his position to make a political decision.

Morrison came under fire on Wednesday for calling NSW police commissioner Mick Fuller to discuss an active investigation into one of his cabinet ministers, Angus Taylor.

NSW police set up strike force Garrad to investigate whether Taylor’s office came to rely on a falsified document to attack Sydney lord mayor Clover Moore for her travel-related carbon emissions.

Morrison called Fuller before announcing to parliament that he was standing by Taylor on Tuesday. His predecessor Malcolm Turnbull said he would never have made the call, because the inquiry needs to be seen as independent and free of political influence.

Ipp, who served on the NSW court of appeal and as an Independent Commission Against Corruption commissioner, said the call was clearly not appropriate. He said it appears to have been made to aid Morrison’s party-political decision-making, rather than the interest of the state.

“An ordinary citizen would not be able to get that information from the police … so what is it about the prime minister that entitles him to that information?” Ipp told Guardian Australia.

“You can’t see that it’s information that relates to matters of state interest. It can only relate to matters of party interest. If it relates to matters of party interest then he’s using his influence as prime minister to try to obtain the information so that he can make the politically correct decision – that is, whether to keep Taylor or to fire him.

“I don’t think that’s appropriate. It’s not appropriate.”

Morrison and Fuller have a pre-existing relationship. Fuller told Sydney’s 2GB radio station last year that he used to be Morrison’s neighbour, and that the prime minister had collected his bins when he went away.

“He was the treasurer at the time,” Fuller said at the time. “He did tell me recently that he’s the prime minister now, and that should be Josh Frydenberg’s job, but he won’t take my calls! He’s a neighbour of mine and I do wish him well – he’s a very good neighbour.”

Guardian Australia approached Fuller for comment but was yet to receive a response.

Fuller did, however, tell the Australian that the conversation with Morrison was “extremely short” and one that gave “no more or less information than what was in the media release”.

“You can’t have a police commissioner making decisions to [conduct] an open and transparent investigation then suggest there’s something inappropriate in relation to receiving a phone call. It’s hypocrisy to say that,” he told the newspaper.

“It was an extremely short conversation in that he just wanted confirmation we were conducting an investigation.”

Ipp said the controversy was the kind that could be investigated by a properly constituted federal anti-corruption commission.

He said calls of the type Morrison made were extremely rare.

“No premier, certainly in my experience in NSW, would ever dared to have called up and said how far is the investigation gone on this and what are you going to do about it?” he said.

“But the prime minister is apparently able to do it with the NSW police, and that in this day and age leaves one with a rather uncomfortable feeling.”