Malcolm Turnbull has expressed confidence in the special minister of state, Mal Brough, after the Australian federal police sought documents relating to his role in the release of the former speaker Peter Slipper’s diary.

The prime minister said there was nothing to suggest Brough should stand aside from his ministerial position “at this stage” – but added that the Queensland-based MP should provide “complete cooperation with the investigation”.

Brough issued a statement on Thursday saying he was willing to meet with the AFP to discuss claims relating to his contact with Slipper’s former staffer James Ashby. Brough, who won Slipper’s former seat of Fisher in the 2013 election, confirmed his home was one of the properties covered in search warrants executed on Tuesday.

“I can confirm reports that the AFP visited me on Tuesday requesting any documentation relating to allegations involving the disclosure of diary notes of Mr Slipper,” the Liberal National party MP said.



“I can also confirm that I provided the exact same material to the AFP as I previously provided to the federal court. Furthermore I advised the AFP that I would be happy to meet with them at any time in the future if need be.”

Turnbull was asked about the implications of the AFP investigation when he addressed the media on the sidelines of the Apec summit in the Philippines.

“Mr Brough has stated, and I’ve got no reason to doubt him, that the material that they’ve received is the same as has been already made public, so there’s nothing new in that,” the prime minister told reporters in Manila on Thursday.

“There is an ongoing inquiry there and the answer is yes, I do have confidence in Mr Brough, but of course there are rules relating to ministers and cabinet ministers. But at this stage there’s nothing to suggest that Mr Brough should stand aside or do anything of that kind. Naturally he is providing complete cooperation with the investigation, as he should.”

The Labor leader, Bill Shorten, said the AFP visit was “not a good look” for the minister responsible for government integrity.

“He and Christopher Pyne and Wyatt Roy need to just come out and spell out their role working with James Ashby in bringing down former speaker, Peter Slipper,” Shorten said.

When asked whether Brough should step down while the investigation was under way, Shorten said: “I don’t know about that … sometimes in politics we can overcomplicate issues can’t we? Just tell us what happened. Tell us what happened.”

Guardian Australia revealed in September that the AFP was actively investigating the alleged unauthorised disclosure of Slipper’s diaries, a year after receiving a complaint about the issue.

The controversy was revived in September 2014 when the Nine Network’s 60 Minutes program broadcast a lengthy interview with Ashby, who described his communications with Coalition MPs Pyne and Roy about arranging for a lawyer to assist him.

The Labor MP Graham Perrett wrote to the AFP the day after the program went to air, pointing to Brough’s response when the journalist Liz Hayes asked: “Did you ask James Ashby to procure copies of Peter Slipper’s diary for you?”



Brough replied: “Yes I did.”

The AFP also searched Ashby’s parents’ home on Queensland’s Sunshine Coast on Tuesday. “As these warrants relate to an ongoing investigation, it is not appropriate to comment further,” the AFP said at the time.

A one-page extract of the warrant, published by the Australian newspaper, suggests the AFP is investigating whether Brough “counselled and procured” Ashby to disclose extracts from Slipper’s 2009 to 2012 official diary and provide those extracts to third parties without authority “contrary to section 70(1) of the Crimes Act 1914 by virtue of Section 11(2) of the Criminal Code 1995”.

It also suggests the AFP is investigating whether Brough “counselled and procured” Ashby to access restricted data “contrary to section 478.1 of the Criminal Code 1995 by virtue of section 11(2) of the Criminal Code 1995”.

In media interviews after being sworn in to Turnbull’s ministry in September 2015, Brough defended his conduct, saying the claims about the diary were a “misunderstanding”.

He wrote to the prime minister on 25 September to assure him that the Australian federal police had not approached him. “My solicitor has contacted the AFP and, on the advice available to me, I can confirm that I am not under investigation,” he wrote at the time.

“If approached, I would, of course, cooperate with the AFP.”

Ashby launched a sexual harassment case against Slipper, then speaker of the House of Representatives, in 2012, which led to Slipper standing aside and ultimately resigning from the key parliamentary position.

In December 2012, the federal court judge Steven Rares threw out the case on the grounds of abuse of process, finding Ashby had launched proceedings “to pursue a political attack against Mr Slipper” and had acted “in combination” with another staffer and Brough.

Rares’s orders were subsequently set aside, but Ashby ultimately decided against continuing with the case.

Brough, a former minister in the Howard government, lost his seat of Longman in 2007 but returned to parliament when he defeated Slipper in the seat of Fisher six years later.

Having backed Turnbull’s challenge against Tony Abbott’s leadership in September, Brough was elevated to the position of special minister of state and was also appointed as the minister for defence materiel and science.

The special minister is responsible for the administration of parliamentary entitlements.

Perrett questioned why Brough had not stood aside from his position, given his particular ministerial responsibilities.

“I can’t imagine how he can say, ‘while the AFP are raiding my house I can also provide advice on other things’,” Perrett said on Thursday. “It just seems bizarre that he wouldn’t have stood aside.”

Perrett added that Coalition figures, including Abbott and Pyne, had been “quite vociferous when it came to the speaker, Peter Slipper, standing aside” in 2012.

Ashby told the ABC on Tuesday he was “shocked” and “disappointed” by the AFP’s decision to search the Beerwah home where his parents live and where he works. He said the AFP was looking for evidence of communication with Brough, Pyne and Roy and reporters.

Pyne, who is the minister for industry, innovation and science, and Roy, the assistant minister for innovation, have not commented on the developments.