'I'm probably the most casual Prime Minister NZ has had' - Key responds to ponytail-gate

John Key says being "New Zealand's most casual Prime Minister" played a part in him inappropriately touching an Auckland waitress's ponytail last year.

Prime Minister John Key says he “needs to make sure he is a bit more careful.”

Speaking with ONE New Political Editor Corin Dann on TVNZ's Q & A programme this morning, Mr Key described himself as a "friendly guy who likes to interact with the public".

"I do have a bit of a laugh and I'm probably the most casual Prime Minister New Zealand's ever had," Mr Key said

"There's been some real advantages of that, occassionally there's some disadvantages."

Waitress Amanda Bailey provided a detailed account of Mr Key's actions on the left-wing blog The Daily Blog last week and says the ponytail pulling took place over a period of several weeks in 2014 in the build up to the election campaign.

Mr Key says he regrets pulling Ms Bailey's hair and he hopes what's become known as 'ponytail-gate' hasn't damaged his credibility as Prime Minister.

"Clearly I've completely misread the situation. I have to take total responsibility for that.

"I shouldn't have done the things I've done and obviously I regret that and I regret any harm that that's caused the young lady in question."

Mr Key says he's learned from the situation and will be "a bit more careful" in the future.

"You can't reverse things that have happened as much as you 100 per cent might want to.

"But what you can do is learn from them. I have to mark this down as something I got wrong and therefore have to learn from it."