Queensland's deputy premier has been referred to state parliament's ethics committee over the purchase of a Brisbane investment property.
The Crime and Corruption Commission in September cleared Jackie Trad over the purchase of the Woolloongabba property, which is along the route of the state government's Cross River Rail project.
However, parliamentary speaker Curtis Pitt has confirmed that the purchase would be referred to the ethics committee over issues raised by the CCC investigation.
"I have reached the conclusion that there are sufficient questions of fact to be determined against the evidence such that it would be prudent to refer the matters to the Ethics Committee for further consideration," Mr Pitt said in documents tabled on Friday.
"I also wish to stress that I have not taken this decision lightly, and I have given this decision lengthy and serious consideration."
Ms Trad has since sold the property for no more than the $695,000 paid for it in March.
The purchase plunged the state government into an integrity crisis over the Woolloongabba fixer-upper Ms Trad said her husband bought with a family trust.
Ms Trad issued a public apology after admitting she failed to properly declare the purchase of the Woolloongabba home, which may have increased in value because of its location on the route of the Cross River Rail project she was overseeing at the time.
She said she had erred in failing to declare the purchase within the required time, and Premier Annastacia Palaszczuk later stripped her of responsibility for the rail project.
The deputy premier has promised to cooperate fully with the ethics committee investigation.
"The CCC found there was no evidence of corrupt or dishonest conduct in the Deputy Premier's late lodgement of paperwork relating to the purchase of a property," a spokesman for Ms Trad told AAP.
"As the matter is now before the ethics committee, it would be inappropriate to comment further."
Opposition leader Deb Frecklington, who spent weeks demanding Ms Trad's resignation, says it is another test of the premier's leadership.
"This has never happened before in Queensland politics and shows how deep the integrity crisis goes in the Palaszczuk government," she said.
"The Premier must finally act and sack dodgy Jackie Trad.
"Jackie Trad's position is untenable as a decision-maker while this investigation is taking place."
While Queensland's corruption watchdog found no evidence to support a finding of misconduct, it did raise serious concerns.
It recommended changes to the way conflicts of interest are dealt with, including criminal penalties for MPs who fail to declare such conflicts or update their register of interests.