National wants the Iranian diplomat who delivered a "hate speech" against Jews at an Auckland mosque expelled from New Zealand.

Reports that Hormoz Ghahremani made the fiery anti-Israeli speech alongside Holocaust-deniers surfaced late last month.

Jewish community leaders and Race Relations Commissioner Dame Susan Devoy reacted strongly, and the Ministry of Foreign Affairs and Trade said it had "conveyed its concerns" to the Iranian Embassy.

Opposition foreign affairs spokesman Gerry Brownlee says the diplomat made what was effectively a hate speech, and racial disharmony offences under the Human Rights Act are quite clear.

"It raises questions as to why Foreign Affairs Minister Winston Peters hasn't already required the withdrawal of the diplomat's credentials and his removal from the country," he said on Friday.

"Diplomats have a privileged position in most societies, allowing them to best represent the relationship between the country they're from and the country they're posted to.

"Inciting racial tension by making anti-Semitic statements is the antithesis of that important role, regardless of the context or setting in which the comments were made."

Brownlee was Foreign Minister in the previous government.

- NZ Newswire