TVNZ's controversial host Paul Henry - famous for lampooning everyone from Susan Boyle to overweight children to Greenpeace activists - has had a taste of his own medicine after falling victim to a prankster on this morning's Breakfast show.

The state broadcaster sent out a press release apologising for screening Mr Henry's interview with a young man purporting to be a whaling supporter named Jay Pryor, who said he was launching a pro-whaling petition.

"Paul Henry's suspicions were raised during the on-air interview because of the interviewee's lack of knowledge, despite a Breakfast producer having spoken to "Jay Pryor" the night before the interview and believing he was plausible," said TVNZ publicist Andi Brotherston.

"We do not know whether the person spoken to by the producer the previous night was the same person who appeared on Breakfast," Ms Brotherston admitted.

Mr Henry told that Breakfast was alerted to Jay Pryor and his pro-commercial whaling group by a Sunday News article and presumed the group was legitimate because of it.

"It all added up," said Mr Henry. "There was a website, he'd put out press releases and then there was the newspaper story. He'd gone to more lengths than most people would."

Choosing a timely issue and promoting a view that wasn't entirely implausible also helped the man's air of legitimacy, said Mr Henry.

But his suspicions were raised by his interview subject's lack of knowledge on the issue, said Mr Henry. "His arguments were enormously superficial. It was like shooting fish in a barrel."

Asked whether he thought enough was done to vet the prankster before interviewing him, Mr Henry said "in hindsight, no. But hindsight is a wonderful thing."

He also denied he was embarrassed by the prank, which he thought was "harmless".

While at TVNZ, the prankster had his photo taken with Prime Minister John Key, who also appeared on Breakfast this morning. Ms Brotherston said the Prime Minister's office had been advised of the hoax.

A press release purporting to be from Commercial Whaling New Zealand, released following the programme, said the Prime Minister had told the prankster he supported his views.

TVNZ said it was reviewing its set-up interview procedures as a result of the prank, and apologised to viewers.

"Jay Pryor" has set up a website,, and following this morning's programme sent out a press release.

"Commercial Whaling New Zealand (CWNZ) launched its petition today with a live interview with Paul Henry on TV One's Breakfast programme," said the release.

"After the interview, CWNZ's Jay Pryor spoke privately with Prime Minister John Key, who expressed his support for the IWC's Commercial Whaling proposals. Key told Mr Pryor that the issue was very sensitive with the New Zealand electorate, but that commercialization [sic] was the best option for the future of whaling."

TVNZ said it believed the prankster was comedian Guy Williams, who was chosen as Dai Henwood's protege on a C4 show last year.