A contestant on My Kitchen Rules NZ styled as a sophisticated snob from a plush Auckland suburb has posed in hundreds of hardcore pornographic photos.

Katrina Dunlop, 27, admitted she posed for the explicit porn magazine and website NZX Online after being strapped for cash.

"It was six or seven years ago, and you know like it was so long ago and I haven't done anything illegal and it was a one-off," said Dunlop.

"But don't worry, I will be wearing clothes on TV. I wouldn't do it again, and I'm not proud of it, but I did it."

TVNZ said they were unaware of the explicit images and were left scrambling when alerted on Friday.

"Katrina has today confirmed to TVNZ that she was, six years ago, involved in a photo shoot for an adult magazine and pay-per-view website," a spokeswoman said.

"Our production company's screening process includes criminal record checks for which this activity is not relevant. Katrina told us that she regrets the shoot but was in a difficult financial situation and that it was a life lesson she has moved on from."

This is the latest in a string of reality TV contestant screening gaffes this year, which included a convicted fraudster starring on The Bachelor and a man convicted of manslaughter starring on The X Factor NZ.

Family First NZ spokesman Bob McCoskrie said allowing people with "dubious backgrounds" to star on reality TV shows was negligent on the part of production companies.

"I'm very surprised that the production company doesn't have a more stringent vetting process," he said.

He added that contestants on shows like MKR NZ usually achieve a high public profile, and in this case, it could draw unwanted attention to the pornographic images.

"While hardcore porn may not be illegal, there is still a stigma against it quite rightly and it is unacceptable to so many families," he said.

"They don't want any connection between someone who is obviously making money through posing for hardcore pornography and is now on a family cooking show. That is a really bad link."

Dunlop, who lives in Remuera and is a mother-of-two and has a stepson, said her family and husband were aware of the X-rated photos.

"At the time financially things weren't the best. I bought a house when I was 20 ... we needed the money so I did it," she said.

Now, working as a model and actor, Dunlop and her sister Natasha Gorrie will host their MKR NZ instant restaurant on Tuesday night.

She said the pair were portrayed as snobs on the show, but the reality was "just so far away from that it's not funny".

"I'm just a mum, a busy hard-working mum who loves to cook," she said.

On the MKR NZ website, Dunlop and her sister were described as two beauties who love the finer things in life – clothes, hair, makeup and food.

"Incredibly driven, these sophisticated sisters from Remuera know what they want – elegance and perfection. They have high standards and if they aren't met, rest assured, they will let it be known."

It is understood Dunlop shot three sets of the hardcore photos under the name K*Leigh. There are more than 700 explicit images of her - where she is described as an Auckland brunette babe - which can still be viewed online.

The three photoshoots included pornographic scenes with another woman in a kitchen and at an Auckland beach.

Dunlop has worked as an actor and model, and was in a recent photoshoot for a Housing New Zealand campaign.

She lists Shortland Street, Go Girls and The Jono and Ben Show among her acting credits.

The TVNZ spokeswoman said she hoped people would still support Dunlop and her Gorrie when they host their instant restaurant on Tuesday night.

SECRET SHAME OF REALITY TV

- The Bachelor contestant Danielle Le Gallais failed to disclose to Mediaworks she had served 18 months in jail for fraud. She turned down the offer of a rose early on in the show.

- A front-runner on The Bachelor, Danielle Robinson, had a drink-driving conviction which she declared to producers during the screening process. Robinson was left ring-less in the show's final episode.

- X Factor NZ contestant Shae Brider was jailed for six years for manslaughter in 2004 after a fatal stabbing. He said he had been upfront with producers for the Mediaworks show, and had "nothing to hide". He later apologised on the show, and said he regretted appearing on TV.

- Former Masterchef contestant Victoria Koszegi was caught more than five times over the drink-drive limit after filming wrapped up. She was booted from the show in August and denied the charges of driving with excess blood alcohol and careless driving.