The MP for the Sydney seat of Bennelong could be a a UK citizen by descent through his English-born father

This article is more than 2 years old

This article is more than 2 years old

Liberal MP John Alexander is checking whether he is a dual citizen, according to a Fairfax Media report noting his father was born in Britain and is likely to have conferred citizenship by descent on him.

If Alexander establishes he holds British citizenship it would trigger a byelection in the Sydney seat of Bennelong, which is held on a margin of 9.72%, and further imperil the Coalition’s grip on power after the high court ruled Barnaby Joyce was not eligible.

The report states that Alexander’s father, Gilbert Alexander, was born in Essex, England in September 1907 and migrated to Sydney when aged three.

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A spokesman for John Alexander reportedly said: “He believes his dad renounced his UK citizenship in the 41 years he lived in Australian before John was born.”

However the report said Alexander had confirmed he had not renounced any British citizenship before entering parliament, and could not say definitively whether his father did so before his birth in 1951.

“But of course [Alexander] will fully participate in the process that the [prime minister] has just announced today,” the spokesman said.

In an updated statement, Alexander said his father was born in the UK in 1907 before moving to Australia “as a very young child”.

“He became an Australian citizen as soon as he could,” he said. “I understand he renounced his British citizenship before I was born, because he was a proud Australian.”

“I was born in 1951 as an Australian citizen.”

On Monday Malcolm Turnbull unveiled a new disclosure process that would require parliamentarians to state the date and place of birth of themselves and their parents, and provide evidence of renunciation of foreign citizenship.

Asked how confident he was that Coalition MPs were not foreign citizens, Turnbull said: “The federal director has told me that all of the Liberal party members believe that they are in compliance with the constitution.”

Section 44 of the constitution states that people who hold foreign citizenship are incapable of election to parliament.

Although Gilbert Alexander reportedly arrived in Australia in 1911, a distinct category of Australian citizenship was only recognised in 1949, which implies he may only have had a two-year window to renounce British citizenship before John Alexander was born in Sydney in 1951.

Responding to the government’s proposed new transparency measure, Bill Shorten questioned why Turnbull had opposed Labor’s “universal disclosure” proposal on Friday, only to change his mind on Monday.

He suggested Turnbull’s previous “reluctance to act meant he was hiding someone”, and accused him of a “dramatic about-face”.

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The inner metropolitan seat of Bennelong is a culturally diverse area taking in suburbs on Sydney’s lower north shore including Denistone, Epping, Meadowbank and Ryde.

Labor held the seat between 2007, when Maxine McKew defeated John Howard, and 2010, when she lost it to Alexander.

In 2016 Alexander won Bennelong with a primary vote of 50.41% and a two-party preferred result of 59.72%.

Guardian Australia has contacted Alexander for comment.