The Australian Federal Police has added more confusion to the question of whether the AFP consults ministers before conducting raids, after its outgoing commissioner, Andrew Colvin, denied that it did so.

On the ABC’s 7.30 program on Monday, Colvin was questioned about the recent raids on the ABC and on News Corp journalist Annika Smethurst over leaked documents. Colvin was asked whether any government minister was consulted about the raids in advance.

He said it was “normal business” that ministers were not consulted.

“This is police business and we don’t consult with ministers before we do that.”

But a spokesperson for the AFP told Guardian Australia each investigation had different circumstances.

“The AFP determines when the minister’s office should be notified of any activity based on the individual circumstances of each investigation,” they said.

Last year it was revealed that the office of the home affairs minister, Peter Dutton, was informed in advance about a raid on the home affairs department during an investigation into the leak of damaging information about the au pairs visa scandal.

Text messages obtained by BuzzFeed News under freedom of information laws revealed that AFP deputy commissioner Neil Gaughan tipped off Dutton’s chief of staff, Craig Maclaughlan on 10 October, the day before the raid.

“That warrant activity will now be first thing tomorrow morning,” Gaughan said.

“Thanks mate – this arvo also fine,” Maclaughlan replied.

Gaughan responded with a thumbs-up emoji.

Dutton has continually denied being informed of the raid, even if his office knew in advance.

Gaughan’s text message sparked a formal complaint from the officer whose home and workstation was searched as part of the raids, according to Nine newspapers, stating the text message “provides me reasonable grounds to suspect the AFP is neither operationally independent or without political bias”.

The AFP told the Senate standing committee looking at whether the documents seized were privileged material that the practice of informing the minister’s office was standard policy for matters that were considered politically sensitive.

Speaking to Ray Hadley on radio 2GB on Thursday, Dutton insisted politicians had no role in the recent media raids.

“It’s a matter for the AFP and that’s as it should be,” he said.

“In our country we don’t have politicians directing who can be investigated or arrested or raided etc. They’re entirely matters for the police and that is how it will continue and the thought of interfering in a police investigation has never crossed my mind and it won’t – that’s the reality – not just from a moral stance, but that’s the law in our country.”

Guardian Australia has sought comment from Dutton’s office.