John Tamihere has been slammed by the Holocaust Centre of New Zealand, after he used a Nazi slogan at an Auckland mayoral debate.

On Tuesday evening, Tamihere and Phil Goff took part in a debate in Ponsonby's Chapel Bar during which they discussed transport, infrastructure and other topics.

Near the end of the event, both candidates were asked to answer the question, 'what do you wish for the grandchildren of Auckland?'

Goff said his soon-to-be-born grandson, who is of mixed-race parentage, will represent the future of Auckland.

"Well I say Sieg Heil to that," Tamihere replied, shocking the audience.

Holocaust Centre of New Zealand chief executive Chris Harris said Tamihere's use of Nazi language was "wrong" and "deeply irresponsible".

Harris said Tamihere was inciting hate in one of the world's most ethnically diverse cities. 

"It is utterly unacceptable for a public figure to evoke Hitler and the Nazis as Mr Tamihere is doing."

'Sieg Heil', which means 'hail victory' in German, was a common rallying cry for members of the Nazi Party, often accompanied by a salute.

It's unclear what Tamihere meant by the remark. His campaign has been approached for clarification.

In 2008 the then-Labour MP drew the ire of the Jewish Council when he said he was "sick and tired of hearing how many Jews got gassed".