Queensland LNP senator Matt Canavan has resigned as the minister for resources and northern Australia after being told by the Italian embassy that he is an Italian citizen.

But unlike two Greens senators who immediately quit parliament after discovering their dual citizenship, he is not resigning from the Senate but waiting for the High Court to make a judgment about his status.

Canavan told a news conference called late on Tuesday he had become aware “that according to the Italian government, I am a citizen of Italy”.

But Attorney-General George Brandis said it was the federal government’s preliminary view that Canavan was not in breach of Section 44 of the Constitution – which bans dual citizens standing for parliament – because the registration of Italian citizenship was obtained without his knowledge or consent.

In the latest – and most bizarre yet – twist in the citizenship imbroglio, Canavan, 36, who was born in Queensland, said that in 2006 his mother, born in Australia of Italian parents, 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.”

While he knew his mother had become an Italian citizen, “I had no knowledge that I, myself, had become an Italian citizen – nor had I requested to become an Italian citizen”.

He said that after Scott Ludlam and Larissa Waters resigned over their dual citizenship his mother on Tuesday evening a week ago raised with him the possibility that he was an Italian citizen.

“I have since then taken steps to check my citizenship status with the Italian authorities and that has confirmed that I was registered as an Italian citizen in January 2007.

"The Italian authorities have confirmed that the application for Italian citizenship was not signed by me. To my knowledge, until this week, I have not received any correspondence from the Italian authorities about my citizenship status, and they have not been able to provide any such records.” He has never been to Italy.

Canavan said that while he didn’t intend to resign from the Senate, given the uncertainty around his status he would stand aside until the matter was resolved and resign as minister.

Brandis, appearing with Canavan at a joint news conference at which they did not take questions, said the government had taken advice from the solicitor-general and was in the process of taking advice from experts in Italian citizenship law.

“It is the government’s preliminary view that, because the registration was obtained without senator Canavan’s knowledge or consent, that he is not in breach of Section 44 of the Constitution.

"Nevertheless, in view of the legal uncertainty concerning the matter, when the Senate convenes on Tuesday week, the government will move to refer the matter for determination by the High Court,” Brandis said.

Malcolm Turnbull said Deputy Prime Minister Barnaby Joyce would be acting resources and northern Australia minister until Canavan’s status was resolved.

Waters, who quit parliament a week ago after finding she was a citizen of Canada, which she left as a baby, tweeted:

Ludlam resigned after finding he was a citizen of New Zealand, which he left as a child.