Calls intensified for Australia\'s parliamentary speaker to step down after claims he sexually harassed a male staffer in a case that could hurt the nation\'s fragile government. Reports on Saturday alleged Peter Slipper sexually harassed former staffer James Ashby, including telling him to shower with the door open when he stayed at his home, and \"moaning\" in a sexual manner after asking him for a massage. Slipper, 62, was also accused of misusing taxpayer-funded taxi services. The ABC Sunday said 33-year-old Ashby, who is openly gay, had launched legal action under the Fair Work Act detailing alleged explicit text messages, unwanted sexual advances and inappropriate comments towards him. The married Slipper arrived back in Australia from the United States on Sunday and made no comment but in a tweet denied all the allegations, saying they were \"a surprise to me.\" The conservative opposition demanded he be removed from parliament until the issue was resolved as earlier claims of sexual misconduct from 2003 involving him and another male staffer emerged. In that incident, reports said a video existed of Slipper lying on a bed with a junior male staffer, hugging him \"in an intimate fashion\". \"If the speaker will not voluntarily stand aside while these allegations are being resolved, the prime minister must indicate to him that she will act to force him to stand aside,\" opposition leader Tony Abbott told reporters. \"This is a question of the prime minister\'s judgment, her integrity, her sense of the standing of the parliament and she cannot afford to wash her hands of this.\" Slipper defected from Abbott\'s Liberal Party last year so he could be appointed speaker. It stripped one vote from the opposition and shored up Gillard\'s ruling Labor Party\'s wafer-thin hold on power. If he is forced to stand aside, Labor would have to appoint one of its own MPs as speaker, reducing its numbers in the lower house. Deputy Prime Minister Wayne Swan said Slipper was entitled to the presumption of innocence while the matters were before the court. \"I\'ve been in parliament a long time. I\'ve seen allegations come and go. These are now allegations that are in legal proceedings,\" he said. \"We should respect those legal proceedings. We should respect those processes.\"