Australian parliament speaker steps down over sexual harassment allegations

In a statement issued on Sunday after returning to Australia from the United States, Slipper "emphatically" denied allegations he sexually harassed a former staffer and misused taxpayer funded taxi dockets.

However, he also said it was appropriate for him to relinquish his duties as speaker while the lawsuit is being sorted. The 62-year-old former opposition MP sits as an independent, and became speaker of the lower House of Representatives in November 2011 with Gillard's backing, a move which forced his resignation from the conservative opposition.

He is being sued by a former male staffer, 33-year-old James Hunter Ashby, over sexual harassment allegations in a suit filed in Australia's Federal Court in Sydney on Friday. 

Ashby also alleges misuse of taxpayer funded taxi dockets by Slipper in the lawsuit.

"The allegations include both a claim of criminal behaviour and a claim under civil law," Slipper said in the statement. "As such I believe it is appropriate for me to stand aside as speaker while this criminal allegation is resolved."

The Labor government has an effective majority of one and depends on independents for support. The speaker's casting vote can be significant in the event of a tie, where the speaker traditionally votes with the government.

Deputy Speaker Anna Burke is to act as speaker for the interim. Slipper said he intended to resume his role as speaker eventually.

Opposition leaders have called on Slipper to resign his seat, a move which would force a critical by-election.

"This is a very, very serious situation where allegations of the gravest kind have been made against the speaker of the parliament," said opposition leader Tony Abbott.

The row is embarrassing for Gillard, who is struggling after months of poor polls.