Prime Minister Julia Gillard on Tuesday dismissed as "disgraceful" an opposition claim that she was making light of sexual harassment by allowing the parliamentary speaker to hold his job while facing allegations that he pressured a staffer for sex.

House of Representatives Speaker Peter Slipper stepped aside Sunday while police investigate allegations leveled by a former staffer that Slipper misused taxi payment vouchers while traveling by limousine in Sydney this year.

The staffer, James Ashby, 33, is also suing Slipper in the Federal Court for sexual harassment, alleging that Slipper only employed him as a media adviser in pursuit of sex. Slipper, 62, who is married with two adult children from a previous relationship, denies all the allegations.

Opposition leader Tony Abbott has said both the criminal investigation and the civil case should be resolved before Slipper returns to the speaker's chair.

Gillard "is essentially making light of sexual harassment" by arguing that Slipper could serve as speaker while facing the civil charges, Abbott said Monday.

Gillard responded Tuesday in Singapore, telling reporters, "That's a disgraceful allegation and it's exactly what we expect from Mr. Abbott: continued negativity."

The government argues that while senior officials should stand aside while facing criminal charges, there was no precedent for them to do so in the face of civil suits.

Government figures hope Slipper will be quickly cleared by police of the fraud allegations so that he can return to the chair before Parliament resumes on May 8. The opposition wants a no-confidence vote against Slipper, but would need support from several independents to win.

Slipper defected from the conservative opposition in November last year to accept the prestigious 324,000 Australian dollar ($426,000) -a-year job, which has limited voting rights. While he is sidelined, a member of the ruling center-left Labor Party will take the seat, effectively depriving the government of a vote in the closely balanced Parliament.

Slipper is an unwelcome distraction for Gillard's government, which has long trailed the opposition in opinion polls. Many commentators say the government faces a crushing defeat at elections due next year.