Documents have emerged showing One Nation senator Malcolm Roberts once was a British citizen.
The Queensland senator has denied on several occasions he ever held British citizenship.
"I have never held any citizenship other than Australian," Senator Roberts tweeted on October 25 last year.
One Nation leader Pauline Hanson told The Australian newspaper last week there was "no evidence" her party colleague was ever British.
But Buzzfeed has obtained an immigration department document signed by Senator Roberts and dated May 8, 1974, on which the then 19-year-old notes he is a "British UK and Cols (Colonies)" citizen.
Senator Roberts was born in Disergarh in India in 1955 and his family arrived in Australia in October 1962.
In another document, Senator Roberts' father Leuan, who was born in Wales, signs consent for his son to apply for Australian citizenship.
While the documents confirm the Roberts family's notifications to become citizens were approved by the immigration department, there is no mention of whether the British citizenship was extinguished.