Opposition Leader Bill Shorten has accused former Labor MP Craig Thomson of betraying the entire union movement and his political party.
The disgraced former MP's actions in misusing union funds were a "deep and unforgivable betrayal" of Health Services Union members and the Labor Party, Mr Shorten told parliament on Monday.
"It is a terrible shame that Craig Thomson's reprehensible behaviour has besmirched the reputation and cast doubt on the motives of the (union) movement," he said.
"Mr Thomson abused the trust of this place, his constituents, his colleagues and thousands of hard-working Australians in the health services sector."
Labor supported "without qualification or reservation ... or equivocation" a motion of regret for a now-infamous defence statement Thomson made in parliament on May 21, 2012, when he emphatically denied fraud allegations and named and blamed other people.
The House of Representatives apologised to Health Services Union members and people for the "egregious falsehoods" Thomson said in naming them in the statement.
The House also apologised to HSU members for Thomson's decision to spend $267,721.65 on his election campaign in 2007 and for his fraudulent use of union funds.
Thomson, who entered parliament in 2007, was convicted of fraud charges by the Melbourne Magistrates Court last week.
He is awaiting sentence on multiple theft and fraud convictions including using a union credit card to pay for prostitutes.
Mr Shorten had no doubt HSU members suffered as a result of Thomson's actions and the former MP owed them a deep and heart-felt apology.
"I hope that this motion can assist the members of the Health Services Union who have been let down and betrayed by Mr Thomson," Mr Shorten said.
Minister Barnaby Joyce said Mr Shorten's speech was perfect, but came two years too late after Labor had persisted in supporting Thomson.
House leader Christopher Pyne said parliamentary privilege should only be used in defence of constituents and not as a weapon to attack opponents who couldn't fight back.
He never wanted anyone to misuse the power in the same way Thomson had, he told parliament.
"He was listened to in eerie silence," Mr Pyne said of Thomson's statement.
"We gave him that respect and he returned the favour by misleading the parliament, by defaming individuals who couldn't defend themselves under parliamentary privilege."
Mr Pyne demanded Mr Shorten pay back to the HSU the $267,000 spent on Thomson's election campaign.
The government successfully referred Thomson to parliament's privileges committee on Monday, saying there was a prima facie case that he had misled parliament during the speech in which he protested his innocence and advanced alternative theories about the incidents.
Thomson faces up to six months in jail or a $5000 fine if found to have deliberately misled parliament.
