An anti-violence organisation for which the Prime Minister is an ambassador asked for an explanation after he was caught up in a radio station stunt that referenced prison rape.
White Ribbon said it asked John Key about his appearance on The Rock on Wednesday, which led to a petition for him to be dropped as an ambassador for the charity.
"We have reached out to the Prime Minister, and we are informed that he did not know what was about to occur, and did not at the time comprehend the rape references or make any. We take the Prime Minister at his word," the charity said in a statement on its website.
"As a result of this incident, White Ribbon will be writing to all our ambassadors to remind them of our expectations, and the commitment they have made to the campaign. Our and their pledge is to never commit, condone or remain silent about violence towards women. We will continue to try and uphold that."
Last Wednesday, Mr Key was taking part in an interview at the Rock when he was persuaded to enter a cage that had been brought into the studio.