Treasurer Josh Frydenberg has revealed for the first time that his mother did not lose her Hungarian citizenship until 1948 – after the end of World War II – despite claims she was stripped of it by the Nazis when she was born in a Budapest ghetto.

The new information is contained in an updated filing that Mr Frydenberg has prepared to answer questions over his eligibility to sit in Parliament under Section 44 of the Constitution.

Mr Frydenberg is facing new questions over his citizenship following revelations of a push to ask the High Court to consider the matter under a Court of Disputed Returns filing.

The Treasurer has consistently stated that his mother, Erica Strausz, who arrived in Australia as a 7-year old child, had papers that were marked “stateless”.

Her family had reportedly been interned in a Budapest ghetto by the Hungarian fascists, before finally making her way to Australia after time in a displaced persons camp.

In a fiery denunciation of questions over Mr Frydenberg’s citizenship last year, former prime minister Malcolm Turnbull said Ms Strausz was never a Hungarian citizen.

“Josh Frydenberg’s mother Erica Strausz was born in 1943 in the Budapest ghetto. That is where the fascists had pushed all the Jews in together, as a prelude to sending them to the gas chamber,” Mr Turnbull told The Guardian in 2017.

“She wasn’t a Hungarian citizen when she was born, neither were her parents – you know why? The Hungarian fascist government, allied with Hitler, stripped Jews of all of their rights, the right to citizenship and the right to life. Her family fled Hungary at the end of the war. It was a miracle they weren’t killed as so many of their relatives were.

“So Erica Strauss came to Australia as a stateless person. She had no citizenship. She came to Australia, she became an Australian citizen and she is Josh’s mother.”

However, Mr Frydenberg’s own updated filing states that his mother was a Hungarian citizen from 1943 to 1948. It does not include further information on how she was rendered stateless after World War II ended.

Victorian lawyer Trevor Poulton said there were now plans to challenge the Treasurer’s Kooyong election in the High Court.

“Josh Frydenberg has been totally evasive about how his mother was rendered stateless,” Mr Poulton told The New Daily.

“Finally we get a date and it’s 1948. That’s 2.5 years after World War II ended. This is not about a family fleeing the Holocaust.

“So you’ve got this discrepancy. On what basis does a family in 1948 suddenly lose their citizenship rights?”

“It doesn’t make sense. You can’t be escaping the Holocaust in 1948.”

Mr Poulton, who has written a novel called The Holocaust Denier, denied claims he was motivated by anti-semitism.

“No, I am not anti-semitic. I haven’t got an anti-semitic bone in my body,” he said.

“I’ve written a novel, it’s fiction.”

Mr Frydenberg’s earlier documentation to Parliament in 2017 said that he had sought legal advice confirming he was not a Hungarian citizen by descent, but did not include information on his mother’s citizenship.

The survival of the Treasurer’s family was a miracle given the massacres of thousands of Jews during the period and the transportations to Auschwitz that began in early May 1944.

It is estimated that of the 800,000 Jews in Hungary at the beginning of the war just over 200,000 survived.

Mr Frydenberg again denied on Tuesday that his citizenship is an issue, insisting the matter had been dealt with during the last Parliament.

“These issues were dealt with comprehensively through the last Parliament, and the Coalition is confident that none of its members or Senators have issues in that regard,” he said.

“No-one should deny what was an appalling and tragic event in world history. And it wasn’t just the Jewish people who were the victims of the Holocaust. It was many other minority groups.

“It’s a tragic period in world history. It should never be forgotten, nor forgiven.”

Mr Frydenberg has previously produced immigration entry documents from 1950 that describe his mother as stateless.

As a result, he has argued that his mother is not a Hungarian citizen and that he cannot be by descent.

The Coalition has repeatedly attacked any suggestion of a question over his citizenship as “absurd”, “offensive” and even anti-Semitic.

Prime Minister Scott Morrison slammed the reports at the time as hysterical.

“I mean frankly, the suggestion is pretty offensive in regards to Josh and his family history,” Mr Morrison said.