The Government has dismissed suggestions Prime Minister Julia Gillard knew about the Craig Thomson credit card sex scandal case before it became public.
A news report today claims Ms Gillard's chief of staff when she was deputy prime minister rang the industrial registrar in 2009 to ask whether he was investigating Mr Thomson over alleged misuse of his former Health Services Union credit card.
Mr Thomson, now a Labor backbencher, is accused of using the credit card to pay for prostitutes and for personal withdrawals totalling more than $100,000.
Mr Thomson denies any wrongdoing and has not been charged over the allegations.
Opposition Leader Tony Abbott seized on the media report today, saying that Ms Gillard's office knew about the case before it was reported.
"I think she owes it to the public to tell us exactly what she knew, when she knew it and what she did about it," Mr Abbott said.
But Senate committee documents show that the industrial registrar communicated with the deputy prime minister's office on April 8, which was the day the story broke.
"No other communications concerning this inquiry have taken place," Fair Work Australia states in the document answering committee questions.
Cabinet Minister Craig Emerson said the story was "quite a ridiculous one" to infer Ms Gillard's staffer had tried to interfere with an investigation.
Dr Emerson said Ms Gillard's chief of staff was only phoning to see whether reports that the union was being investigated were true.
"That was the end of the matter," Dr Emerson said.
Ms Gillard said her chief of staff had no specific recollection of phone call, but that was because it is "completely unremarkable for a chief of staff to ring a public servant to check a fact".
It was not the same, she said, as shadow attorney-general phoning the NSW Liberal government to warn them he was asking for a NSW Police investigation.
"But let's be clear about this," Ms Gillard said.
"My chief of staff, chiefs of staff in other ministerial offices, now and for decades and decades in the past and for decades and decades to come, ring public servants to check facts."