Australian dual citizen MP Joyce wins back seat

Australia former Deputy Prime Minister Barnaby Joyce has claimed a stunning victory in his New South Wales seat.

Prime Minister Malcolm Turnbull labelled it the biggest by-lection swing to a sitting government in Australian federal political history.

Joyce was formed to quit when it was revealed he held dual Australian-New Zealand citizenship, a revelation that disqualifed him from parliament.

But he has since renounced his New Zealand citizenship, and on Saturday won back his New England seat.

In what will be a major shot in the arm for the government and could restore some confidence after a grim few weeks, Joyce appears to have lifted his primary vote by at least 10 points, meaning after the distribution of preferences he will have as many as seven in 10 votes in the NSW seat.

That represents a swing of at least 11% and possibly as much as 14% on a two party-preferred basis compared with the 2016 election.

It comes despite the government's flaccid fortunes lately and the unusual circumstances of Mr Joyce losing his seat to the citizenship crisis.

The dual citizenship crisis has cost eight MPs, including Joyce, their seats and the government its majority.

Joyce claimed that he never knew he had inherited New Zealand citizenship from his father.