Jacinda Ardern officially offers Stephen Colbert Hobbiton citizenship on the Late Show

Prime Minister Jacinda Ardern has used a popular US TV show to invite comedy duo Flight of the Conchords over for dinner.

Appearing as a guest on the Late Show with Stephen Colbert, Ms Ardern also extended the popular TV host an official invitation to become a citizen of Hobbiton.

After grilling New Zealand's leader about US President Donald Trump being laughed at by United Nations diplomats a day earlier, Colbert played her a video of Bret McKenzie and Jemaine Clement from the previous episode of his show.

"Hey Jacinda, we have an important question for you. Can we come for dinner?" the Flight of the Conchords stars asked in the clip.

Ms Ardern said she was happy to have them over for dinner "if they pick me up from the airport".

"I've met them before. It's New Zealand, so we all know each other."

Colbert is a renowned fan of Sir Peter Jackson's The Hobbit and Lord of the Rings trilogies and, of course, steered the conversation in that direction as soon as he could.

"You have an impressive resume, but perhaps most impressive to me is that you could technically be described as a hobbit. I understand you grew up near Hobbiton?" asked Colbert.

"I did," responded Ardern, before adding, "I do find it slightly offensive that everyone think that every New Zealander starred in either Lord of the Rings or The Hobbit."

Without missing a beat, Colbert then asked, "Were you in Lord of the Rings or The Hobbit?"

"Some of us auditioned but weren't successful," said Ms Ardern.

Colbert confessed to Ms Ardern that he was "a little bit obsessed" with the films and books of Middle-earth.

"I've heard about that. The people of Hobbiton have heard about it as well and they contacted me today to say they'd like to make you a citizen of Hobbiton," said Ms Ardern.

"I have it in writing, but actually they're going to have the official calligrapher of Lord of the Rings, The Hobbit and Hobbiton write up your official invitation. So come to New Zealand, we'll make the ceremony official."

Also during the interview, Colbert seemed impressed by Ms Ardern's relaxed attitude toward being addressed by her first name, and about people walking up and saying 'hi' in New Zealand.

"I've stopped and had conversations in the most awkward of situations - maternity bra shopping," Ms Ardern said.

"I don't think you'd find Donald Trump doing that," said Colbert.

Ms Ardern was the Late Show episode's second guest, following Murphy Brown star Candice Bergen.