An embarrassed TVNZ has been forced to apologise to viewers after it was duped into running a live-to-air interview with a pro-whaling lobbyist who turned out to be a fake.

The man - pretending to be Commercial Whaling New Zealand spokesman Jay Pryor - was invited on to Breakfast yesterday morning, where he was interviewed by host Paul Henry on the benefits of commercial whaling.

But it was all a hoax. "Pryor" was comedian Guy Williams, who was working for a rival network.

"As a result of this prank, Breakfast is reviewing its set-up interview procedures and apologises to viewers for the error," said TVNZ spokeswoman Andi Brotherston yesterday.

"The man had gone to reasonable lengths to dupe the public by creating a false name and setting up a fake website."

TVNZ ran the interview after "Pryor" was profiled in a Fairfax-owned Sunday newspaper article at the weekend.

Brotherston said staff went through normal vetting procedures and checks, but they would be reviewed.

"It appears that the person who has duped us orchestrated a tissue of lies and duped us because that's what they set out to do.

"What do you do when somebody deliberately sets out to deceive you?

"We think our procedures are robust but we're reviewing them to see whether there's an extra layer of vetting that we can add to it.

"It's very clear in the interview that Paul did that he didn't believe the guy. He was extremely sceptical."

A transcript shows the interview ran full course, and Henry then discussed the "lobbyist's" aims with co-host Pippa Wetzell.

Using the name Commercial Whaling New Zealand, "Pryor" claimed that legalising the practice would create a financial incentive for whalers to kill the animals in a more sustainable way.

Henry told him he was "promoting the plundering of whales".

After the programme, Henry said he was immediately suspicious because the group had a valid, but weak argument.

"Talking to the guy on air, it was like shooting fish in a barrel.

"You couldn't have a decent argument with him because he didn't have a reasoned, thought-out argument himself so there was nothing you could really counter, there was no opportunity for intellectual debate.

"We are presenting the rich tapestry of New Zealand life on air every morning five days a week and part of that rich tapestry obviously, are kooks."

Williams rejected Henry's response.

"Paul Henry did not catch on to me. It was not until an hour later after the show had finished that they stripped it off the internet.

"[The news bulletin] had my story in it every 20 minutes up until they found out it was a hoax.

"I'm very opposed to the way these shows carry themselves, you just see the crap they're putting on there and I thought: 'I'll give you some more crap' ..."

Williams said he asked to speak to John Key, who was in TVNZ's offices and the Prime Minister obliged.

Mr Key said yesterday he told the prankster New Zealand would like to see no commercial whaling, and believed diplomatic approach was the way to achieve this.

"He's a hoax, so I think we should take him with a high degree of scepticism," said Mr Key later.

It is understood the interview will be used in C4's comedy show The Jono Project.

But the "Pryor" interview is not the first time Henry has been taken-in. Henry interviewed author Kevin Abdulrahman on his show in June, 2008, as part of a publicity drive for a new self-help book.

Abdulrahman claimed to be giving away a Ferrari to one of his readers.

However, the Ferrari was bought with borrowed money, and shortly after the publicity stunt, it was listed for sale on Trade Me.

It is not known if TVNZ reviewed its policies following the interview. TVNZ have been called for comment today but have so far not returned phone calls.