But Puhinui School mother Angela Suamasi says the company's branding is inappropriate for young children.

"I agree with the reading incentive - that's awesome," she says. "It's more what Hell Pizza stands for. So that's my concern.

"They want to send our babies to Hell Pizza to introduce them to their menu [items], which are Lust, Envy, Gluttony etcetera, and their kids club is called 'Satan's Little Helpers'. Come on."

Ms Suamasi says she made a formal complaint about the programme to the school's Board of Trustees in an effort to get the promotion banned.

"For me it's about who's giving that incentive. It could be Boobs on Bikes. Where does it stop? They're only primary kids."

But Principal Kevin Hornby has told Ms Suamasi the programme is optional.

"The involvement in the reading wheel promotion is certainly not compulsory," Mr Hornby said in an email to the mother. "If you don't want [your daughter] involved because of your view of Hell Pizza as a food outlet, that is absolutely fine and something that I can understand.

"Puhinui School, along with many other schools, see the promotion as an opportunity to promote mileage and consequently improve reading.

"We have had much feedback through both teachers and parents as to the success of the incentive of a pizza for children to read more books, which is the reason that we initiated the programme."

The school has declined to comment further on the issue.

Hell Pizza says while there have been concerns from a few parents over its branding, the response to its reading promotion has been overwhelmingly positive.

"The vast majority of people are so supportive," says Hell Pizza general manager Ben Cumming.

"We are regularly emailed and contacted by parents and librarians and teachers to thank us for the challenge and share their stories with how it really has improved their child's love of reading and just got them more interested in books."

Mr Cumming says the New Zealand Book Awards Trust was interested in working with Hell because of the "edginess" of its brand.

"It's getting harder with modern technology to pry kids away from screens...A lot of people in the industry were very supportive of it and made a big point of saying what a huge difference it was making to promote books in New Zealand."

He says the company is not going to try to change upset parents' minds over its brand.

"What I would say is to go into it with an open mind see it for the benefits of what the promotion gives to the kids and the libraries and the schools who are involved in it."

Newshub.