Jacinda Ardern had to call and apologise to fiancé Clarke Gayford twice after letting wedding details slip

Jacinda Ardern has revealed she had to call her fiancé Clarke Gayford and apologise after letting slip their wedding details not once but twice.

The Prime Minister announced in May the couple had set a date for their summer wedding, over two years on from when Gayford proposed over Easter weekend in 2019.

While appearing on The AM Show on Monday she wouldn't confirm the date as she hadn't yet told her guests, but she did reveal the nuptials will take place in Gayford's hometown of Gisborne.

Ardern told More FM's Breakfast Club on Wednesday the media had been door-knocking her Parliament colleagues asking for details, but she has been the only one to let them slip.

"On two occasions I've had to call Clarke and say 'I'm sorry I accidentally gave away our wedding destination on national television this morning'. It's my fault [some of the details are out there]. I can't blame anyone else."

Luckily, Gayford was okay with it.

"He's been quite forgiving," she said. "I told him I swore we had already told everyone where we are getting married and he just said 'no, no we hadn't'."

Ardern told the Breakfast Club she had enlisted her family and friends to help them plan.

"We have my mother in law and my sister in law and some amazing friends who live in and around the area we are going to be married in so we are calling in a few family favours."

Gisborne's mayor Rehette Stoltz told The AM Show she was delighted to hear the couple will tie the knot in the area, and revealed her top picks for when and where it would be.

"You would like to get married in summer time so hopefully around early January, after Rhythm and Vines as no one would really like their wedding while there are 30,000 other people here," she said.

"We have fabulous venues around here - farm settings, or country settings, or the Prime Minister may even go up the coast. We have three-and-a-half hours worth of fabulous coast up north. Lots of options to choose from."