Key Points:

National leader John Key says if campaigners get enough support to force a referendum on so-called smacking laws, the referendum should be held at this year's election.

Prime Minister Helen Clark yesterday indicated a referendum was unlikely to be held at this year's election, even if campaigners had enough signatures on their petition, because of the organisation it would take to stage a referendum.

Campaigners yesterday handed in their second attempt at a petition to force a referendum on the issue.

An earlier attempt this year failed when too many signatures were ruled invalid.

Kiwi Party leader Larry Baldock handed over more than 390,000 signatures backing the call for a referendum on the question: "Should a smack as part of good parental correction be a criminal offence in New Zealand."

The Office of the Clerk in Parliament has two months to check the petition is signed by 10 per cent of registered voters or around 290,000 valid signatures.

If the threshold is met, the Government would have one month to name a date for a referendum.

Mr Baldock is hoping it would coincide with this year's election, but the Government can delay any vote on the issue for up to a year.

Asked yesterday why it could not be held alongside the election, which must be held by November 15, Miss Clark replied: "Just in terms of sheer organisation, I do not think that is possible."

But Mr Key today told reporters that if the campaigners have the numbers, it should be held at the election this year.

"Well, the referendum should take place at the general election in 2008 and quite frankly the behaviour of the prime minister smacks of arrogance and wasteful behaviour," he said.

The legislation, which was drafted by Green MP Sue Bradford, amended section 59 of the Crimes Act to remove the defence of reasonable force for parents who physically discipline their children.

National supported the legislation after an amendment gave police discretion to judge whether a reported offence warranted prosecution.

Mr Key said his position on the child discipline legislation was clear.

"But this is about democracy, the right of people to be heard and it's the absolute height of arrogance that the prime minister is going to use a technicality within the law to circumvent people's rights to express their views on the issue."

It could take up to two months to check off the signatures on the petition but "ultimately it's about putting on the ballot paper at election time a pretty straightforward question".

Mr Key said the law, which is a year old, seemed to be working well.

Deputy Police Commissioner Rob Pope yesterday said police had undertaken a second review of the impact of the law.

During the first three months of the review period there had been an increase in the number of smacking events attended by police but this number had decreased during the second three-month period to levels like that before the law was passed.

Mr Pope said even with the increase the numbers were still very small, and there had been some smacking cases around the Christmas/New Year period which was typically a stressful time for some families.

Mr Baldock today said Miss Clark's claims were ridiculous.

He said an answer on the success or failure of the petition had to be given by August 23, allowing more than two months until the latest possible election date.

"You can't tell me that it will take more than two months to organise one simple question to be added to the ballot paper."