Right to Life New Zealand says it will request a review of the chief censor's decision to allow the release of a controversial euthanasia book.

The Peaceful Pill Handbook, co-authored by Australian euthanasia advocate Dr Philip Nitschke, was initially banned, but was resubmitted for classification after sections were blacked out and changes were made.

The Office of Film and Literature Classification classed it as objectionable, saying it must be sealed and have an R18 label on its cover before being allowed to be sold in NZ bookshops.

Chief censor Bill Hastings said although the book was "well intentioned", it could significantly increase the risk of young people killing or harming themselves and had potential to greatly disturb or shock them.

The book contains details about how to commit suicide, including how to travel to Mexico to buy Nembutal, which some New Zealanders have done.

Associate Minister of Health Jim Anderton said the book was likely to have "unintended consequences" but was not prepared to second-guess the chief censor's decision.

Right to Life New Zealand spokesman Ken Orr questioned the government's response to the decision.

"It is incongruous that on one hand we have this dangerous book being allowed for sale in New Zealand and on the other hand we have the government earlier this year unveiling its five-year plan which includes expensive TV advertising to reduce New Zealand's suicide rate," Mr Orr said.

He said the book was "a threat to the lives of the vulnerable in society and is injurious to the common good".

"Right to life believes that there is no right to encourage another person to commit suicide."

Orr said Right to Life challenged the chief censor's statement about the book being "well-intentioned" and said the organisation would lodge a request for a review of the "misguided" classification.

Community values organisation, The Society for the Promotion of Community Standards, also said it would request a review of the classification.