Matthew Canavan has quit as Australia's Minister for Resources and Northern Australia in a row over dual citizenship - the country's third politician to do so in recent weeks.
The 36-year-old said he was unaware his mother had applied for him to get Italian citizenship when he was 25.
But he said he would not be resigning as senator until he had legal advice.
Under Australia's constitution, a person cannot run for federal office if they hold dual or plural citizenship.
Earlier this month, two senators from the Australian Greens party were forced to resign for holding dual citizenship.
In a statement posted on Twitter on Tuesday, Mr Canavan said: "In 2006, my mother lodged documents with the Italian consulate in Brisbane to become an Italian citizen.
"In doing so, it would appear that she made an application for me to become an Italian citizen as well. I was 25 years old at the time."
Mr Canavan, who is a member of the Liberal National Party, said his mother raised "the possibility" that he was an Italian citizen last week, although he had not signed the application.
The politician - who was born in Australia and says he has never been to Italy - said that "given uncertainty raised by this matter" he was resigning as minister.
But he stressed that he was not quitting as senator because he had not yet obtained "definitive legal advice as to whether my registration as an Italian citizen, without my knowledge or consent, was valid under Italian law".
So, what does Australia's constitution say on this issue?
The Section 44 (Disqualification) states that any person who "is under any acknowledgment of allegiance, obedience, or adherence to a foreign power, or is a subject or a citizen or entitled to the rights or privileges of a subject or a citizen of a foreign power... shall be incapable of being chosen or of sitting as a senator or a member of the House of Representatives".
This is interpreted by the High Court of Australia as meaning that persons with dual citizenship are not permitted to run for office.
Are there any other countries with similar restrictions for dual citizens?
Yes. Dual nationals cannot be elected to parliament in Armenia, Egypt or the Philippines.
In Israel, a person must renounce his or her other citizenship to be sworn is as a member of Knesset (parliament).
In New Zealand, serving lawmakers run the risk of losing their seat if they renew non-New Zealand passports.
In the US, only citizens born on American soil can become president or vice-president.