Federal Parliament Speaker Peter Slipper has stepped aside while investigations are underway into allegations of sexual harassment and fraud against him.

Mr Slipper, who returned to Australia today, released a statement saying he "emphatically" denied allegations he sexually harassed a former staffer.



"The allegations include both a claim of criminal behaviour and claim under civil law," he said.



Any allegation of criminal behaviour was grave and should be dealt with in a manner that showed appropriate regard to the integrity of Australia's democratic institutions and to precedent, he said.



"As such, I believe it is appropriate for me to stand aside as Speaker while this criminal allegation is resolved."

Peter Slipper in Los Angeles yesterday. Credit:Channel Ten

The allegation by former aide James Ashby was incorrect, Mr Slipper said.



"Once it is clear they are untrue I shall return to the Speakership," he said.



"In relation to the civil matter there will be an appropriate process that will resolve the matter in due course."



In the meantime Labor MP and Deputy Speaker, Anna Burke, will act as Speaker, Mr Slipper said.

Mr Ashby, 33, reportedly launched legal action in the Federal Court on Friday alleging the Sunshine Coast MP had made unwelcome advances towards him and had sent him sexually explicit text messages.