Malcolm Turnbull put up a spirited defence of his country's deportation policy which has seen criminals with Kiwi citizenship sent to New Zealand if if they have barely lived there.

He was questioned about it during a press conference with Prime Minister Jacinda Ardern in the gardens of Kiribilli House on the edge of Sydney Harbour.

But he was interrupted by a boatload of sightseers just offshore who started chanting partway through the press conference.

Newstalk ZB political editor Barry Soper asked the question of Turnbull, saying while it was legal, was it moral to maintain the policy when the New Zealand citizenship of some of the deportees was "about as sound as Barnaby Joyce's was".

Advertisement

Turnbull said yes and there was a right of appeal, of which just under 40 per cent were successful.

"The process is a fair and just one."

When the chanting sightseers interrupted, he suggested they might be Kiwis.

Ardern said she accepted the Australia Government was well within its rights to exercise it deportation policy.

But she had raised it again today, particularly the cases of people who had never lived in New Zealand, to make sure the Australian Government was "aware of our perspective on it and our strength of feeling around it but ultimately it is in the Australian Government's hands to determine how they manage that policy".

Turnbull stress that the policy did not just apply to New Zealanders. It applied to non-citizens who had committed serious offences.

"I can entirely understand how keen an issue it is in New Zealand but it is our sovereign right, as it is yours, to determine whether and in what circumstances non-citizens can remain within our borders, or yours in New Zealand.

When Soper persisted, Turnbull suggested he might be well placed to take up negotiations on their behalf.

Advertisement

Over a 1000 criminals have been deported to New Zealand since a law change in 2015 in which visas were automatically revoked for offenders who served over a year.

Turnbull also put up a spirited defence of the offshore detention of asylum seekers on Papua New Guinea and Nauru, after a question asked by an Australian reporter who referenced New Zealand's offer to take 150.

Turnbull said before the offshore process there had been 50,000 illegal arrivals by boats, and 1200 deaths at sea. The policy allowed Australia to be in charge of its own borders rather than people smugglers.

The two Prime Ministers later addressed a lunch of 1000 business people where they said they had agreed to investigate ways to boost the transTasman flow of business and exports from Small and Medium sized Enterprises (SMEs).

"About 75 per cent of New Zealand SMEs export to Australia and more Australian firms export to New Zealand than any other country," Ardern said.

"I see this as the next step in CER and an extension of the potential that exists in the agenda for a Trans-Tasman Single Economic Market (SEM).

She said she and Turnbull agreed to commission a joint programme of work to investigate the factors that helped to contribute to the success of SMEs across the Tasman, and to work through the factors that are constraining their success.

"We have also agreed to jointly commission a review of our policy and regulatory frameworks to ensure that they are creating an environment in which trans-Tasman digital trade is as open and facilitative as they are for conventional trade."

The lunch was attended by many business leaders, as well as the 250 business and community delegates at the Australia New Zealand Leadership Forum.

New National Party leaders Simon Bridges spoke at the forum this morning and attended the lunch.

Bridges said later it was important that his first speech outside New Zealand was to business and growth and opportunity.

"I talked about Bill English and John Key's legacy and the state we'd left New Zealand in We are a much more confident and aspirations country.

"I outlined our pretty straightforward approach to Opposition which is to support things good for growth, oppose things that aren't and put forward our own ideas and try and get support for those."