UPDATED 2.43pm: An award-winning but controversial children's book has been taken off the selves while its classification is reviewed.

Family First New Zealand won its bid for an Interim Restriction Order for 'Into the River' by Ted Dawe.

The story tells the tale of a young boy, his sexual encounters and drug use.

The Censorship Office first classified the book as unrestricted with a note about explicit content in 2013 when it first hit shelves.

Since that time it has received more than 400 complaints.

The decision of the censor will now be reviewed by the Board of Review.

Family First's National Director Bob McCoskrie said the book describes sex and drug-taking in very explicit detail.

"Freedom of expression shouldn't trump protection of kids and also the public good. But we're also challenging the process whereby the censor can undermine a decision made by the Board of Review."

"The Board has made a decision based on an appeal, but then the Censor's office has come and undermined that appeal. It shows that there's problems with the process as well."

But Author Ted Dawe said the ban on his award-winning book is extraordinary and impedes on freedom of speech.

"It's extraordinary," Mr Dawe said. "I've had quite a few emails from people who share that sense of outrage. Do we live in a country where books get banned? I'll get burnt next."

His disbelief is shared by the Association of New Zealand Book Sellers with spokesman Lincoln Gould saying it is "bewildering" that an order has been placed on the book.  

"I'm just totally opposed to any idea that looks to banning books," said Mr Lincoln.  

Mr Dawe added it was not easy to write a book that teenagers would want to read, or to get it published.

"The book was never about sex and drugs, it was always about bullying people and how that damages people for the rest of their lives. That is really the underlying theme, everything else is just the trappings that go along with that."

Media law expert Professor Ursula Cheer has said its even illegal to share the book with a friend if you have it.

It's the first time a book has been banned in New Zealand for 22 years.