Australian deputy PM says he may not be eligible for parliament

Deputy prime minister Barnaby Joyce has referred himself to the High Court over the possibility he may be a dual citizen.

According to section 44 of the Constitution Senators and members of Parliament are forbidden from being citizens of a country other than Australia.

Barnaby Joyce looks set to the latest MP to caught out over his citizenship, with reports emerging that he's asked the High Court for advice on whether he's a New Zealand citizen.

Prime Minister Malcolm Turnbull said Mr Joyce should remain as Deputy Prime Minister because the legal advice was so strong.

The deputy prime minister is not on any list of New Zealand citizens but because his father was born there he is considered by the NZ government, in preliminary advice, to be a citizen.

Mr Joyce dropped the bombshell in Parliament at 10am Monday.

He will not step down as deputy prime minister while the High Court considers his eligibility to sit in the parliament.

Greens Senators Scott Ludlam and Larissa Waters were forced to resign after it was revealed they held New Zealand and Canadian citizenship respectively.

He said his father was born in New Zealand but moved to Australia in 1947 "as a British subject - in fact we were all British subjects at that time".

The Turnbull government has a one seat majority in the House of Representatives.

"Neither I nor my parents have ever had any reason to believe that I may be a citizen of any other country", he said.

According to the NZ government passport website: "If you were born overseas and at least 1 of your parents is a New Zealand citizen by birth or grant, you are an NZ citizen by descent".

'I was born in Tamworth, just as my mother and my great-grandmother was born there 100 years earlier, ' he told parliament on Monday morning.

Two Greens senators resigned from parliament last month after discovering they were dual citizens due to their birthplace.

Joyce has already assumed the portfolio responsibilities of his National party colleague, Matt Canavan, who has already been referred to the high court because of his possible Italian dual citizenship.

One Nation Senator Malcolm Roberts has also been referred to the High Court over his British citizenship status.

Vanessa Coleman