The children's commissioner for Wales, Peter Clarke, has joined his three UK counterparts to call for a total ban on smacking children.
Peter Clarke said he believes children need further protection
The UK's four children's commissioners issued a joint statement on Sunday calling for a ban and for the issue to be further debated in parliament.
Mr Clarke told BBC Wales he believed the current law was confusing.
The Department of Education said it was for parents to decide how to punish their children within legal limits.
In a letter to Education Secretary Ruth Kelly, the children's commissioners of Wales, England, Scotland and Northern Ireland said laws on smacking should be changed as a matter of "fundamental principle".
Legislation in Wales and England, which was tightened in 2005 allows parents to hit their child mildly as a "reasonable punishment".
Laws on smacking have been tightened in Wales and England
But Mr Clarke said: "There's still a great deal of confusion in the minds of both parents and the public as what one can do and can't do in terms of reasonably disciplining children.
"We also think that children as the smallest members of our communities should have the right to be protected from physical assault.
"It seems to us that the best way to do that is to bring forward a law that clarifies it."
Mr Clarke said he wanted to see MPs allowed a free vote in parliament on the issue.
'Change of attitude'
He added: "What (a law change) does do is send out a clear signal and clarify what is and what is not legal.
"It's in that context that we will see the last bit of the change of attitude that I think really has already happened in this country.
"The fundamental message we are giving out is that hitting people is wrong and that children are people."
The Department for Education and Skills responded in a statement.
It read: "We do not condone physical punishment for children but it is for parents to decide.
"They have to think carefully about the law on assault and make sure that chastisement does not get to that point. If not they will be prosecuted."
In 2003, the Scottish Parliament voted to restrict the scope of "reasonable chastisement" by setting out criteria for determining whether an assault on a child was "justifiable".
One year ago MPs voted to restrict "reasonable punishment" in England and Wales.