Key congratulates Turnbull, praises Abbott

Prime Minister John Key has congratulated his new Australian counterpart Malcolm Turnbull after his leadership coup across the Tasman.

"I will call Mr Turnbull today to offer my congratulations," Mr Key said in a statement on Tuesday morning.

Mr Turnbull rolled Tony Abbott on Monday night as leader of the governing Liberal Party, giving Australia its fifth prime minister in five years.

Mr Key said Australia remained New Zealand's closest bilateral partner.

"We enjoy close ties in all areas of our relationship, including in the trade, economic, defence and sporting areas, and I am looking forward to working with Mr Turnbull to advance that."

Mr Turnbull praised Mr Key in a speech following his 54-44 win in a party vote.

"My firm belief is that to be a successful leader ... you have to be able to bring people with you by respecting their intelligence in the manner you explain things," Turnbull said.

"We've got some great leaders in Australia at state level but let me just point to one internationally, John Key, for example.

"John Key has been able to achieve very significant economic reforms in New Zealand by doing just that, by taking on and explaining complex issues and then making the case for them."

Meanwhile, Mr Key also made special mention of his positive relationship with Mr Abbott, who was Australian leader for nearly two years.

"He has been a good friend to New Zealand. He has visited twice this year and our discussions have always been productive.

"I am confident that the close relationship between New Zealand and Australia will continue under Mr Turnbull's leadership."