Almost 90 per cent of people who participated in a referendum asking New Zealanders whether smacking should be illegal have voted no, preliminary results show.

Family First is urging the government to respect public opinion and act on the result.

The $9 million referendum asked: "Should a smack as part of good parental correction be a criminal offence in New Zealand?"

Voter turnout on the initial results was 54 per cent. There were just over 1.6 million votes cast.

The 'NO' camp recorded an impressive result of over 1.4 million, or 87.6 per cent, in the preliminary count, while the 'YES' camp was under 200,000 or 11.81 per cent.

The final result will be declared on Tuesday.

The referendum was organised after Green MP Sue Bradford's member's bill was passed in 2007. That law change amended the Crimes Act to made it illegal for parents to use force against children for correction but also allowed police the discretion not to prosecute inconsequential cases.

There has been criticism of the referendum over concerns some people may have voted no thinking they were supporting the status quo.

The referendum result is not binding on the Government.

Family First director Bob McCoskrie said the government should act immediately to amend the law to allow light smacking and for a royal commission of inquiry into child abuse to be set up.

"(Prime Minister) John Key cannot ignore this result."

Mr McCoskrie said the government should consider this evening's result in light of last year's general election which National won with 45 per cent support.

"The attempt by politicians to dismiss the referendum as 'ambiguous' and irrelevant has also been rebuked by the voters," Mr McCoskrie said.

Those who voted no were not seeking a right to assault or beat children, he said.

"They are simply kiwis who want to tackle the tougher issues of family breakdown, drug and alcohol abuse, mental illness, violence in our media, poverty and stress, and weak family ties."

Mr McCoskrie defended the relatively low turn saying it was still a substantial sample.

"A 54 per cent response rate in the referendum is still significant especially when compared to just 47 per cent voting in the recent Mt Albert by-election, an average of just over 40 per cent voting in the recent local body elections for their mayors and city councils, and a 55 per cent response rate which changed our whole voting system to MMP."

This morning Ms Bradford said not too much should be read into the result.

"I would have a much greater respect for the referendum result if it was based on a clearer question," she said.

"The 'YES' vote is a vote for keeping the law as it is, providing children with the same legal protection from violence as adults.

"Even a large 'NO' vote tonight won't be a clear mandate to the Government to act in any particular way," she said.

Mr Key has said he expected a resounding 'No' vote in the smacking referendum would lead to changes surrounding the law.

He said if the law does not work and good parents get criminalised for lightly smacking a child, the law should be changed.

In the last general election 2.3 million people voted - representing 79.46 per cent of registered voters.