Court disqualifies Australia's deputy PM over citizenship

Australia's High Court has disqualified the deputy prime minister and four senators from sitting in Parliament in a ruling that could cost the government its slender majority in Parliament.

The decision on Friday to disqualify Deputy Prime Minister Barnaby Joyce over a constitutional ban on dual citizens sitting in Parliament means a by-election will be held in December.

Prime Minister Malcolm Turnbull's conservative coalition has a single-seat majority in the 150-seat House of Representatives where parties form governments.

The court also disqualified four of the six senators referred to court including government minister Fiona Nash.

Disqualified senators are replaced by members of their own parties without an election so the balance of power is not altered.

Joyce will be able to stand for re-election, having renounced his New Zealand citizenship.