A farmer at the Morrinsville protest against Labour's water tax is being slammed for his sign calling Ms Ardern a "pretty communist."

When asked what she thought of the sign, Ms Ardern laughed, simply saying "there's your answer".

She then said, "I'm a pretty communist? Did they intend that to be a compliment or an insult? I'm not entirely sure."

An image of the sign was tweeted by Labour's chief of staff Neale Jones, who said if a sign like it appeared at a Labour event he'd ask for it to be taken down.