New Zealand’s Prime Minister Bill English has confirmed that Australia’s Barnaby Joyce is a citizen of the country because his father was born there.

On Monday morning, the Deputy Prime Minister revealed that he was contacted by the New Zealand High Commission last Thursday and advised he “could be a citizen of New Zealand by decent”.

Mr Joyce in turn, argued he was still eligible to sit in Parliament and asked the High Court to make a ruling.

Prime Minister Bill English said he was informed about Mr Joyce’s case late last week and according to local law, he is a New Zealand citizen.

“It is a matter for the Australian system to decide how Australian law applies in his case and how they deal with this issue,” he told reporters.

Under New Zealand law, children born to New Zealand citizens automatically obtain citizenship. It does not have to be activated.

It will now be up to the High Court to decide whether Mr Joyce, in holding dual citizenship, has breached Section 44 of the constitution and is eligible to sit in Parliament.

Meanwhile, Foreign Minister Julie Bishop has accused Opposition leader Bill Shorten of “treachery” today after the revelations a Labor MP prompted a New Zealand Labor MP to probe Barnaby Joyce’s citizenship status.

“Bill Shorten has sought to use a foreign political party to raise serious allegations in a foreign Parliament designed to undermine confidence in the Australian Government,” Ms Bishop told reporters in Canberra.

She also demanded Mr Shorten reveal who made contact with the New Zealand Labor Party.

“Bill Shorten must reveal who he put up to this dirty task,” Ms Bishop said.

“Bill Shorten should be called to account for this appalling behaviour.”

Labor may also find itself in a similar situation over the federal parliament’s growing citizenship scandal, with the government said to be preparing to challenge up to five Labor MPs over their citizenship, including Justine Keay, Susan Lamb, Brendan O’Connor, Maria Vamvakinou and Tony Zappia.

with other agencies