The opposition has targeted Special Minister of State Mal Brough, whose home Australian Federal Police (AFP) raided last week in relation to the disclosure of former Speaker Peter Slipper’s diary extracts.

In parliament, Shadow Attorney-General Mark Dreyfus questioned Brough on whether it was appropriate for a person to ask a Commonwealth officer to produce copies of his employer’s official diary when that officer was not authorised to do so.

Brough has admitted that in 2012 he asked James Ashby, a staffer who had alleged Slipper misused entitlements, to get copies of diary entries. Ashby also accused Slipper of sexually harassing him.

Leader of the House Christopher Pyne suggested the Dreyfus question sought a legal opinion, but Speaker Tony Smith ruled it partly in order.

Brough told the House he had made a full statement on the matter.

Last week, Brough said the police had visited him earlier seeking any documentation about the allegations involving the disclosure of Slipper’s diary notes. Brough said he “provided the exact same material to the AFP as I previously provided to the Federal Court”. He said he had also told the police he would be happy to meet with them at any time in the future if need be.

In a reply to a question from Dreyfus, Prime Minister Malcolm Turnbull told parliament he had confidence in his minister.

Turnbull last week said that “at this stage there’s nothing to suggest that Mr Brough should stand aside [from his ministerial duties]”.

Brough in September last year admitted in a television interview that he had asked Ashby to obtain copies of the diary material. He gave as his reason that he believed Slipper had committed a crime and was defrauding the Commonwealth.

Slipper was found guilty for dishonestly claiming entitlements but this was overturned on appeal earlier this year. The charges were for misusing his Cabcharge allowance in 2010 when he visited wineries around Canberra and dishonestly filled out multiple vouchers.

The police last week also raided the home of Ashby’s parents, which Ashby used as an office.

A search warrant alleged Brough “counselled and procured” Mr Ashby to access restricted data – contrary to Section 478.1 of the Criminal Code – and to disclose extracts from Slipper’s “official diary” without authority – contrary to Section 70 (1) of the Criminal Code.

Slipper was the Liberal member for the Queensland seat of Fisher, but then was enticed by the Gillard government to become Speaker, which improved Labor’s parliamentary numbers in the hung parliament. The Coalition was furious at his treachery and pursued him relentlessly until he was eventually forced to quit the speakership.

Brough, a former Howard government minister who lost his seat of Longman in 2007, won Slipper’s seat in 2013. A Turnbull supporter, Brough was promoted to the frontbench by the new leader.

The parliamentary standing orders mean that there is only a limited amount that Labor can ask about the Brough issue in question time. But Manager of Opposition Business Tony Burke indicated late Monday that he believed there was scope to pursue the matter further during the week.