US television host John Oliver has admitted to a "deep fascination" with John Key - and appealed for Kiwi audiences to find him even more footage of the prime minister to mock on his satirical news show.

The British-born Oliver has regularly featured Key - and more recently, Steven Joyce, when a protester hurled a dildo in his face - on his show Last Week Tonight.

In an interview with Stuff, Oliver said there were two reasons for Key's appeal.

LAST WEEK TONIGHT John Oliver is perplexed by Prime Minister John Key's willingness to answer highly personal questions on a live radio show.

"The first is that New Zealand itself is a genuinely interesting country; the second is that John Key is a very odd human being. It's like a clown car in a circus parade. The car itself is fascinating, but the clown is really the thing that draws your eye. And John Key is nothing if not a gigantic clown."

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Oliver said that Key provided a "wealth of priceless material".

"There's very little that made me happier last year than watching him squawk his way through Maria Carey's All I Want For Christmas."

Oliver chortles like a schoolboy over the fact that there's a world leader prepared to front up to a major media outlet and conjure for the home audience the indelible image of himself standing naked in the shower, having a pee.

John Oliver doesn't mind poking fun at Steven Joyce too.

"My God! What's wrong with this guy? There was another clip where two radio DJs said 'Hey John, will you get in this cage?' and he did it. I couldn't believe it! You're the f***ing Prime Minister! There's a certain dignity in office that you should maintain. Why would you let someone put you in a cage? It was a little bit troubling that the Prime Minister of New Zealand is so susceptible to peer pressure."

Oliver says he's very keen to see more prime ministerial mishaps.

"Please give my love to John Key. He's probably done something dubious in the last 15 minutes that neither of us have found out about yet, so if you hear of anything, I beg you, please let me know."

A spokesman for Key declined to comment.

Last Week Tonight With John Oliver, Mondays at 10.30pm on SoHo