A man tried to jump off NZ Parliament's gallery viewing balcony Wednesday afternoon, causing quite a stir at the parliament, but it was the PM who is now receiving unpleasant remarks and being called "stupid."

MPs let out gasps as a man, muttering about injustices, tried to launch himself from the public gallery into the debating chamber below.

Just when all the attention was on the man, whom the security and protection officers were dragging back over the bannister, PM John Key was heard crying across the house, "shame on Labour."

Since then, Labour leader Phil Goff has called Key stupid, adding he was "stunned" at the jumping man's episode.

"But then the Prime Minister started yelling across the House 'shame on the Labour Party, shame on the Labour Party', as though this was something that was instigated by the Labour Party... Clearly, it wasn't. That was a very stupid thing for him to say," Goff said.

"It was totally inappropriate behaviour for a guy that is the Prime Minister of New Zealand or for any member of the House... He was absolutely wrong. It's a disgrace that he would even make that allegation and I just hope that the election campaign is not going to be fought on that basis," said Goff.

Meanwhile, Auckland solicitor Matthew Piper recalled what happened.

"[He was] obviously trying to propel himself over onto Labour backbenchers at which point the security guards acted very quickly to come and grab him."

The man's whole body was already over the edge of the railing before he was pulled back by four or five people.

"He continued to struggle after he was pulled back over and was making kind of lots of noises about various injustices, no one could really understand."

The security guards did a good job of stopping him, Piper said.