In his only sit-down interview while on his first official visit to New Zealand, UK Foreign Secretary Boris Johnson has spoken about the impact Brexit will have on Kiwis.

Britain is bound to European Union (EU) rules until the Brexit process is over, meaning it can't cement any bilateral trade deals with us just yet.

Mr Johnson told The Nation the UK has an obligation to "take back" its borders during Brexit talks, casting a shadow on visa agreements.

While he said it was too early to say, they "want to have something that is very friendly for New Zealand".

"Obviously there's going to be a trade negotiation, in which I would think the question of the movement of people would be one of the issues."

He said New Zealand is at the front of the queue for a free-trade deal with Britain, but the UK can't sign anything until it has formally left the group.

"We can't sign anything because we have a duty to honour our obligations to the rest of the EU as long as we're in the EU. It would start contaminating the negotiations if we began actively discussing negotiating in parallel with other friends at the same time."

Mr Johnson said he was in discussions with the New Zealand Government, but nothing has been put in ink yet. He added that a visa arrangement for Kiwis would likely come hand-in-hand with a trade deal, once Brexit is complete.

Saudi arms controversy

During the interview he defended the country's sales of arms to Saudi Arabia.

Saudi Arabia has been heavily criticised for its military actions in neighbouring Yemen, as well as its poor human rights record.

The sales have come under fire, with questions around whether they breach international humanitarian law.

Mr Johnson said they "look very carefully at all the contracts all the use of the weaponry that is supplied by the UK".

"We have one of the toughest regimes in the world when it comes to the application of consolidated guidance into breaches of international humanitarian law."

Mr Johnson said the sales deals sit above the line.

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