New Zealand Prime Minister John Key
New Zealand prime minister John Key said he had a 'very warm and friendly relationship' with the café staff Reuters

New Zealand's prime minister John Key has apologised to a waitress for repeatedly tugging on her ponytail for months.

The woman, who has not been named but works in a works in a café in Auckland, accused the premier of "behaving like a school yard bully" while he was on the campaign trail last November.

The waitress wrote an anonymous post for the Daily Blog in which she described how Key was originally just being "playful and jolly" but he continued to pull on her hair on several other occasions.

She said Key only stopped after she warned him "I will actually hit you soon" if he did it again.

Key's office said the prime minister's actions were "intended to be light-hearted".

"It was never his intention to make her feel uncomfortable and he has apologised to her," a statement added.

Key told reporters he enjoyed "a very warm and friendly relationship" – which included practical jokes – with staff at the café .

"I realised she had actually taken offence because it was all in the context of a bit of banter that was going on and so I obviously immediately apologised for that," he added.

Green Party co-leader Metiria Turei said Key's behaviour amounted to "bullying".

She said: "It's a sign of how out of touch John Key has become when he can't even monitor how inappropriate his personal behaviour is, and when people are not comfortable with how he is behaving."

'Such a nice guy'

In her post, the waitress wrote: "In the beginning, the first time he pulled on my hair, I remember thinking to myself he's probably just trying to be playful and jolly, seeing as the general consensus of most who meet him is 'he's such a nice guy'. He's trying to play into that to earn votes, I thought to myself.

"The next time he came up behind me and pulled my hair I was annoyed. Great, I thought, this wasn't just a one-off. Despite my obvious annoyance, I didn't comment on his behaviour. It then happened yet again when he next visited the café and again I didn't respond verbally, but everything about my body language screamed I DON'T LIKE THAT."

She added: "No one else had ever thought it was ok to walk into the café and pull the waitresses' hair, so why did the prime minister think it was ok? My reasoning was simple, I could tell him that I didn't like it – but I shouldn't HAVE to. He was like the school yard bully tugging on the little girl's hair trying to get a reaction, experiencing that feeling of power over her."

She said Key gave her two bottles of his own brand of wine as an apology, a gesture she described as "almost more offensive than the harassment itself".