Prime Minister Jacinda Ardern would not confirm reports of US President Donald Trump mistaking her for Canada's First Lady Sophie Trudeau at the ASEAN summit, today.

It came after comedian Tom Sainsbury told Newshub he was told "Donald Trump was confused for a good amount of time, thinking that she was [Canadian Prime Minister] Justin Trudeau's wife".

On TVNZ1's Breakfast today Ms Ardern was asked by host Jack Tame if the incident happened, after claims she told two people about the possible incident.

"Second-hand, someone observed that they thought that it had happened, but in all my interactions certainly President Trump didn't seem to confuse me when I interacted with him," Ms Ardern said.

"Someone else believed they had observed some confusion."

She would not reveal who the person was that made the observations.

"It's quite complicated Jack," Ms Ardern said when pressed by Mr Tame on the matter.

"They observed what they believed to be a mistaken identity. I then had interactions that suggested he knew who I was, that was the point that I had been properly introduced so that probably cleared it up."

Ms Ardern said she told Sainsbury the "shortened version" of the story behind the scenes at the New Zealand Music Awards.

Ms Ardern told Newsroom at the summit Mr Trump joked, "This lady caused a lot of upset in her country".