ATTORNEY-General Nicola Roxon has denied pressuring a Queensland Labor MP to refer former Howard government minister Mal Brough to the Federal Police over his alleged involvement in the Peter Slipper sexual harassment scandal.

In a letter by Queensland Labor MP Graham Perrett on Friday, Australian Federal Police Commissioner Tony Negus was asked to investigate whether Mr Brough breached the Crimes Act by leaking information from Mr Slipper's diaries to the media.

Mr Brough, who will contest Mr Slipper's seat of Fisher, has been accused by Federal Labor of fuelling a political conspiracy" to bring down the government.

The letter also calls for an investigation into the actions of former staffer James Ashby, who brought the sexual harassment case against Mr Slipper, his colleague Karen Doane and senior Liberal Party figures including Caloundra MP Mark McArdle.

Ms Roxon told ABC radio while she understood the people of Queensland would be "very interested" in the case she had no involvement in the letter.