Queensland Labor MP Graham Perrett wrote to the Australian Federal Police on Friday suggesting that Liberal figures including the Deputy Opposition Leader, Julie Bishop, frontbencher Christopher Pyne, the former Howard government minister Mal Brough and the Queensland Energy Minister, Mark McArdle, may have committed criminal offences by taking part in a ''political conspiracy'' to harm former speaker Peter Slipper and bring down the Labor government.

Mr Perrett wrote that the conspiracy involved using a ''fabricated'' sexual harassment claim by Mr Slipper's former staffer James Ashby to politically damage and humiliate Mr Slipper so badly that he would be forced to resign his seat. In the subsequent byelection, Mr Brough would be elected and would have supported a vote of no-confidence in the Gillard government, enabling Mr Abbott to be installed as head of a Coalition government, Mr Perrett said.

Asked about the allegations yesterday, Mr Abbott said Labor should move on.

''Look, the Labor Party has been hyperventilating about this for months now. They should get over it. They should accept that there has been no conspiracy here,'' he said in Sydney.

''They should understand that the only real issue when it comes to Peter Slipper is why did the Prime Minister ever think he was a fit and proper person to put in that job and, frankly, I think this is all a bit of try-on.''

Mr Abbott questioned whether public servants or ministerial staff had helped with the letter.

''Has any taxpayer money been used to prepare this letter? Have public servants been used to prepare this letter?'' he said.

Mr Perrett, who has been a solicitor since 1999, said he sought input from fellow MPs including the cabinet secretary, Mark Dreyfus, QC, as well as lawyers outside the caucus. He said he had not sought input from public servants or ministerial staff.

''This is the sort of thing that suburban solicitors put together every day,'' he said.

He said he had not sought permission to write the letter but had informed the office of the acting Prime Minister, Wayne Swan.

A spokesman for Mr Swan said: ''Mr Perrett's view is the view of the government: that senior federal Liberal MPs have serious questions to answer about their involvement with Mr Ashby and with this case.''

Mr Ashby's sexual harassment case against Mr Slipper was dismissed on December 12 in the Federal Court. Justice Steven Rares found Mr Ashby devised the claim for political and personal gain in combination with fellow Slipper aide Karen Doane, Mr Brough and Sydney solicitor Michael Harmer. Mr Ashby is appealing the Federal Court decision and announced on Friday that he would pursue his claim through Fair Work Australia.

Mr Perrett said the behaviour towards Mr Slipper could be in breach of laws against causing harm to a person in their capacity as a Commonwealth public official and against unauthorised access to restricted data and unauthorised disclosure of information by Commonwealth officers.