Actor and model Amber Heard has mocked Australia's Deputy Prime Minister Barnaby Joyce after it was revealed that he is a New Zealand dual citizen, a fact which may violate Australia's constitutional rules.

Joyce threatened to have Heard and her ex husband Johnny Depp's two dogs, Pistol and Boo, put down after it emerged that the couple had hidden them from Australian authorities in 2015, which was in breach of biosecurity laws.

The threat forced the pair to make a bizarre apology video.

In a tweet, Heard said: "To comfort Mr. Joyce in his hour need, I have sent him a box of New Zealand's finest kiwi fruit (assuming this passes his biosecurity laws)," accompanied by a picture of the crate of fruit.

Joyce has not responded.

Heard and Depp's run-in with the Australian government made headlines around the world. It had everything: celebrities, dogs, Australians, opportunistic politicians, the threat of animal slaughter, Johnny Depp being forced to look sincere and a fun hashtag: #WarOnTerrier.

Australia gave Heard and Depp a time frame in which to have the two Yorkshire terriers removed from the country. Before they did however, then-Agriculture Minister Joyce threatened to put them down.

"If we start letting movie stars even though they've been the 'sexiest man alive' twice to come into our nation, then why don't we just break the laws for everybody? It's time that Pistol and Boo buggered off back to the United States.

"[Depp's] now got about 50 hours left to remove the dogs. He can put them on the same charter jet he flew out on and fly back out of our nation. He can send them back or we will have to euthanise them."

Joyce's dual citizenship case has been referred to Australia's high court, meaning he may be forced to resign his position.