Key Points:

Opponents of the bill to ban smacking tonight managed to delay a crucial vote in Parliament, winning more time to campaign against the legislation.

National Party MPs fiercely debated clauses during the bill's committee stage and Parliament adjourned before an amendment proposed by Chester Borrows went to the vote.

The amendment would change the bill and allow parents to lightly smack their children.

It was facing almost certain defeat because Sue Bradford, who drafted the bill, had lined up 63 votes against it. She needs a minimum 61 for a majority.

The numbers are unlikely to change before the bill is debated again in two weeks' time, but National MPs are going to put the heat on some Labour members they believe are being forced into opposing the amendment and supporting the bill.

Tonight's delaying tactics also mean the bill's final third reading will not take place until after the Easter recess.

Ms Bradford's bill changes the Crimes Act, removing the legal defence of "reasonable force" for punishing a child.

It means smacking cannot be used to correct a child, although parents will still be able to use "reasonable force" to protect them from harm, prevent them harming others, or to deal with disruptive behaviour.

Opponents say it will turn good parents into criminals, supporters argue it is an essential moved to combat New Zealand's appalling record of child abuse.

During tonight's debate, when opponents made most of the running, passionate arguments were put up that the bill would turn parents into criminals, that it amounted to "home invasion" by the state and that surveys had shown more than 80 per cent of people did not want it.

National MPs said Prime Minister Helen Clark had ordered her MPs to support the bill.

They claimed at least eight -- and they named Dover Samuels, Harry Duynhoven and George Hawkins -- would not have supported the bill if Labour had allowed a free vote.

MPs filed rafts of amendments so that debate could be drawn out, including independent Taito Phillip Field who put in 50 to change the bill's date of commencement.

Labour MPs let the first one go through, which will delay the commencement for a month from the date it passes its third reading, so that the rest became irrelevant.

An attempt by United Future's Judy Turner to have a referendum on the bill was soundly defeated.