The Government has welcomed a U-turn by the United States on its controversial policy of separating children from their parents at the US-Mexico border.

"Separating families at the southern border was concerning to many New Zealanders. New Zealand Cabinet Ministers and MPs were concerned as well," Foreign Affairs Minister Winston Peters said today.

"The coalition Government conveyed its concerns to the US Embassy in Wellington yesterday afternoon," he said.

Ministry of Foreign Affairs and Trade officials phoned embassy officials to relay the Government's views.

"The practice of separating children from their parents and detaining them was simply not a humanitarian approach and any reversal of that practice should be welcomed," Peters said in a statement.

US President Donald Trump signed an executive order today ending the policy which sparked a backlash after images of distressed children being separated from their parents after illegally crossing into the United States appeared in the media.

Following a meeting of Republican politicians, Trump said it was important to be to be strong on border security.

"The Republicans want security, and insist on security for our country. And we will have that at the same time we have compassion, we want to keep families together. It's very important. I'll be signing something in a little while that's going to do that," he said, according to a transcript of his comments.

Under the policy, adults were sent to jail while their children were sent to other facilities.

According to government figures more than 2000 children have been separated from their parents, one reportedly as young as 9 months old, since the policy began earlier this year.

The separation policy sparked a backlash that crossed party lines and drew protests around the country and around the world.

Peters said it appeared Trump had heeded the outcry by signing the executive order which allowed "family unity".

The US earlier this week withdrew from the United Nations Human Rights Council after the UN High Commissioner for Human Rights condemned the separation policy as "unconscionable".

The Human Rights Council is a UN organisation comprising 47 members and is based in Geneva.

Former Prime Minister Helen Clark wondered yesterday whether the US could withdraw from the United Nations all together.

A former contender for the role of UN Secretary-General, Clark said the withdrawal of the US from the Human Rights Council was "a very, very significant step".

Clark said no one was lily white. The US on the council had rightly raised issues about authoritarian regimes but "it also needs to be conscious of the rights of small children being ripped away from their parents".

"It's very hard to say someone's on the side of the angels here and someone isn't."