NSW legislation banning parents from hitting their children above the neck in effect condones physical punishment, a child abuse conference will hear tomorrow.

The 2001 legislation specified where a child could legally be hit, which only perpetuates the view that physical punishment is normal and a parent's right, Bernadette Saunders, of the Child Abuse and Family Violence Research Unit at Monash University, says.

US research shows that physical punishment is ineffective in shaping children's behaviour and could cause long-term psychological harm, she says.

"The legislation may actually have the reverse effect than it intended, it in effect reinforced parents' right to hit children," Ms Saunders said yesterday.

"What it actually says is it's OK to hit your children from the shoulders down, as long it doesn't cause harm lasting more than a short, undefined period of time.

"Children are the only people in our society who can legally be hit. In some states common law exists as a defence to a charge of assault if a parent hits a child in the name of discipline."

Ms Saunders will present the paper, titled Physical Punishment: The Thoughts, Feelings and Words of Australian Children, at the Ninth Australasian Conference on Child Abuse and Neglect, which began at Darling Harbour yesterday.

About 1000 child protection professionals and 60 children from Australia and overseas will attend the four-day conference.

In her opening speech today, the Community Services Minister, Carmel Tebbutt, will tell the conference there has been a "massive increase" in the number of reports of child abuse in the past five years, which she attributes to a rise in inequality across the population, as well as an increase in mandatory reporting.

A spokeswoman for Ms Tebbutt said yesterday that there had been a 436 per cent increase in "reports of concern" to the Department of Community Services.

Ms Saunders said Australia's attitudes on the physical punishment of children, banned in Sweden in 1976, were slowly changing, with the use of implements such as a belt, wooden spoon or garden hose becoming less common.

"There's probably less tolerance of severe physical punishment and the use of implements . . . however there is still a tolerance of smacking children and that'll only change with education and increased parental support," she said.

Research by the Australian Childhood Foundation showed 75 per cent of parents thought it was acceptable to sometimes smack a naughty child, but 95 per cent disagreed with the use of implements, she said.