New Zealand Prime Minister Jacinda Ardern has announced her retirement from politics within the next month.

Ms Ardern choked back tears on Thursday as she said she did not have the energy to seek re-election.

“I know what this job takes. And I know that I no longer have enough in the tank to do it justice,” she said.

She shared a message to her partner, Clarke Gayford, saying: “Let’s finally get married”.