"Jacinda all the best in the election, make sure you do it for all of us," Corbyn said.

Ardern not backing Labour in UK poll

NEW Zealand prime minister Jacinda Ardern has declined to back Jeremy Corbyn, her Labour counterpart in Great Britain, as he campaigns for United Kingdom's top job.

Ardern accepted Corbyn's well-wishes in 2017 when she successfully ran to become New Zealand's prime minister.

Two weeks before New Zealand's election, at the height of Jacindamania, Corbyn was filmed on a London street giving well-wishes to Ardern.

"Jacinda all the best in the election, make sure you do it for all of us," Corbyn said, in a nod to his election slogan of 'for the many, not the few'.

Ardern posted the clip on her Facebook page, noting "From the small world files. A friend had a friend who ran into a Labour friend in London. Thanks Jeremy. Giving it our all."

Asked whether she would vote for Corbyn over conservative prime minister Boris Johnson, Ardern equivocated.

"I'm not a voter. It's a moot point," she said.

"Obviously everyone will know the relationships Labour parties have with other Labour parties but as a matter of course I don't tend to get engaged in other people's elections."

The pair, who share some democratic socialist political views, have been grouped together as new-age transformational leaders.

They have met at least once, with Ardern meeting with Corbyn in April last year during a visit to the United Kingdom.