The ACT Legislative Assembly will investigate a Labor senator's citizenship amid concerns she was ineligible when it sent her to federal parliament.
Former ACT chief minister Katy Gallagher moved to Capital Hill in 2015 to replace Kate Lundy.
Senator Gallagher was re-elected at the July 2016 federal election.
As part of the ongoing dual citizenship saga engulfing federal parliament, she has faced speculation she may be either Ecuadorian through her mother or British via her father.
Senator Gallagher told the Senate in September she and the ALP had legal advice that she was not and never had been an Ecuadorian citizen and that "out of an abundance of caution" she renounced any claim to British citizenship in April 2016.
That was more than a year after the Legislative Assembly chose her to fill the casual vacancy.
"Prior to entering the Senate on a casual vacancy in March 2015, I was not advised that I needed to renounce any entitlement to foreign citizenship," Senator Gallagher said.
Now Liberal MLA Vicki Dunne, who was ACT Speaker at the time, says the assembly may have been misled and an invalid appointment made in light of the High Court's ruling on dual citizenship cases.
ACT politicians decided on Thursday that a committee will examine whether the Legislative Assembly should do more to ensure people seeking to fill casual Senate vacancies are eligible to do so.
It will also look at "whether the previous appointments made by the assembly might be considered in hindsight to be unsound".
Senators have until the end of Friday to report on their citizenship status, any personal circumstances that may affect it, and their renunciation of any eligibility in other nations.
Those records will be published on Monday.