National Party Senator Matt Canavan has resigned from Malcom Turnbull's Cabinet after discovering he apparently holds dual citizenship.
Canavan, a Turnbull Government Minister, will stand aside while he resolves doubts over his Italian citizenship. It follows the resignations of Greens co-leaders Scott Ludlam and Larissa Waters after they both discovered they were dual citizens.
Section 44 of the Constitution prohibits dual citizens from entering the Federal Parliament.
Speaking to the press late on Tuesday, alongside Attorney-General George Brandis, Canavan said he was advised that he holds Italian citizenship after his mother registered the family in 2006 without his knowledge or consent.
"I have become aware that according to the Italian Government I am a citizen of Italy. I was not born in Italy. I have never been to Italy," Canavan said.
"Until last week, I had no suspicion that I could possibly be an Italian citizen. The Italian authorities have confirmed that the application for Italian citizenship was not signed by me."
Following the press conference, Canavan released a statement through his Twitter account, stating that the recent resignations of Waters and Ludlam had prompted his mother to raise the possibility with him of his own dual citizenship.
Brandis says the Government's preliminary view is that Canavan should not be considered in breach of Constitutional rules if the registration for Italian citizenship was made without his knowledge or consent. The Government is consulting legal experts.
"On the basis of the advice the Government has obtained and that George outlined it is not my intention to resign from the Senate," Canavan added.
"However, given the uncertainty around this matter, I will stand aside until the matter is finally resolved and resign as the Minister for Resources and Northern Australia."
Canavan's duties will be taken on by Deputy Prime Minister Barnaby Joyce in the meantime, according to a statement from Turnbull.
"The Deputy Prime Minister, the Hon. Barnaby Joyce, will act in that capacity until Senator Canavan's status is resolved," the statement read.
One Nation Leader Pauline Hanson reacted promptly to Canavan's resignation from Cabinet by asking Malcolm Roberts to further investigate dual citizenship matters in the Senate.
Prior to his election in 2013, Canavan worked as an executive at KPMG and as an economist with the Productivity Commission.
As the Minister for Resources and Northern Australia, Canavan has been in many ways the political face of the Federal Government's support for Adani's proposed Carmichael mine in the Galilee Basin in Queensland.
His tone was triumphal after Adani gave the mine the in-principle go-ahead, and indeed many felt he overstepped the line from celebration to gloating with this tweet, for which he ended up being widely roasted.
The tweet above was hardly a one-off. When Westpac announced it would refuse to fund the proposed mine, Canavan was provocative and defiant, and urged Queenslanders to take their banking business elsewhere.