Donald Trump's New Zealand advisor Chris Liddell has rejected reports that he supported the separation of children at the US border and described it as "terrible policy".

In a rare interview, Trump's deputy chief of staff contradicted reports earlier this year which said he was at a meeting to approve the highly controversial policy and supported it during an informal vote.

"I've been to probably a thousand meetings here … We have never had a vote by hands." Liddell told broadcaster Jack Tame TVNZ's Q+A this morning.

"Had there been a meeting like that, had there been a vote, I would certainly have voted against child separation. I think it was a terrible policy.

"And in fact, my office ran a policy process to come up with an executive order which clarified shortly there-afterwards that child separation shouldn't be part of our policy, so... You know, the damage is done. People report it. I think they reported that I was invited to the meeting, but whatever."

Liddell, who was born in Matamata, is one the president's closest advisors and one of the few officials to survive four years of the Trump Administration. As deputy chief of staff, he co-ordinates policy at the White House and is helping to lead the US response to Covid-19.

In a broad-ranging interview, he admitted that his work for Trump had taken a personal toll, but that it was worth it.

"Look, I've lost friends from being here, I haven't lost my soul … This is a polarising time. And some people have decided that just because I work here, I'm no longer a person they want deal with.

TVNZ broadcaster Jack Tame interviewing Donald Trump's deputy chief of staff Chris Liddell in the White House. Photo / Supplied

He added: "It doesn't make me feel very good. But again, look, I try and look at the bigger picture. I believe in what I'm doing. I'm proud of what I've done here. I've had an amazing opportunity, which I hopefully have done some good with."

Liddell said he liked Trump because he was fearless.

"Would I do the same things the way he did? No. But I think he's made demonstrable progress, and I think he represents a core constituency of this country that desperately needs representing. And so from my point of view, that's worth the bloody noses and the criticism that I get externally for being here."

Liddell shied away from answering questions about Trump's divisive character and controversial decisions, such as failing to condemn white supremacists and challenging the legitimacy of the election process.

"Again, we're in this situation where I'm working here and it's just not a question I really want to get to."

He was also reluctant to discuss the US response to Covid-19, which he was a key part of. There have been more than 245,000 deaths in the US and in the last day alone there were 170,000 new cases.

Liddell said the issue was being politicised and that there would be "plenty of time for post-mortems" next year. He was now focused on getting the US ready for the next "black swan" event or pandemic, saying that countries which had dealt with a serious outbreak in the last 10 years had been better prepared to deal with Covid-19.

"Covid has been a wake-up call to the world...that these types of pandemics are real. And to some extent, we're fortunate that COVID is actually relatively low on the fatality, you know, scale.

"Something bigger and worse may indeed be on the horizon…. That is where I'm spending a lot of my time, not dealing with the politics of who did what."

Liddell has been nominated by the US to become the next Secretary General of the OECD. That nomination has been divisive in New Zealand, because Trump's administration has been hostile to multilateral trade and international entities like the World Trade Organisation (WTO).

Liddell said he believed in free trade but was not a "free trade ideologue". He said free trade was needed after World War Two but its benefits had not been as obvious in the last 20 or 30 years for the US.

"In fact, we've lost something like five million manufacturing jobs here. These are the core middle-class jobs that I talked about and that has had terrible impacts on communities, on mobility and so forth. So free trade — absolutely you should do it, but it should be a means to an end, and it's got to be part of a cocktail of policies."

Trump was not against international organisations but felt many had lost their focus and lost their way, he said.

"Just going along and doing the same old, same old is not the right answer for New Zealand as well. And you know, the OECD budget is about $500 million dollars. New Zealand bears some part of that. So just having international organisations for the sake of it so you can have a discussion forum, is not a particularly good use of New Zealand's resources or time."

He also defended the US Administration pulling out of the Paris Climate Accord, which sets goals for countries to reduce climate-warming emissions. He said the accord was about aspirations, but action was more important.

"There is no way we are on track to meeting the commitments, let alone the target. So, I think the problem that we have is not the aspiration and it's not necessarily— it's the lack of commitment and the lack of domestic policies because, again, Paris accord has some benefits, but it has some real weaknesses.

"It's voluntary. And you actually have to ensconce it in domestic policy. And I see very few countries that are doing that well, including New Zealand, dare I say, if I can be critical of New Zealand.

"Now, New Zealand makes a good case. And I think the Zero Carbon Act was a really good piece of legislation, but it doesn't actually have any teeth. It's an aspiration piece of legislation."

Liddell was born in Matamata and attended Mt Albert Grammar School and the University of Auckland. After working for BECA and Carter Holt Harvey he moved to the US in 2010 and took up senior roles at General Motors (GM) and Microsoft. He began working for Trump in 2017.