Parliament's privilege committee will examine whether disgraced former Labor MP Craig Thomson misled parliament when he emphatically denied fraud allegations.
Thomson, national secretary of the Health Services Union before he entered parliament in 2008, is awaiting sentence on multiple theft and fraud convictions including using a union credit card to pay for prostitutes.
In May 2012 Thomson stood up in parliament to proclaim his innocence, alleging a conspiracy against him.
House of Representatives Speaker Bronwyn Bishop added to Thomson's woes on Monday when she referred him to the privileges committee for investigation.
The decision followed a call earlier on Monday by his successor in the NSW seat of Dobell, Liberal MP Karen McNamara, who said the committee should examine his conduct as an MP.
An earlier inquiry by the privileges committee lapsed with the dissolution of the House of Representatives for the September election.
Mrs Bishop said it was always intended the inquiry would resume when the criminal proceedings were concluded.
Leader of the house Christopher Pyne says the committee will examine whether Thomson deliberately misled the parliament.
"I don't wish to traverse all the details of the sordid and tawdry tale," he told parliament.
But it was perfectly clear parliamentary privilege came with heavy responsibility and needed to be protected.
Mr Pyne said Thomson, in his address to the parliament, named people under privilege and wove an extraordinary tale which many now regarded as fantastic.
"Telling the truth in parliament is an extremely important aspect of the role we play as members of parliament," he said.
Labor is backing the investigation.
"As we supported it in the last parliament, we support the reference in this parliament," manager of opposition business Tony Burke said.
