Children who are spanked or smacked are more likely to exhibit aggression and mental health problems as they grow up, a large-scale study has found.
Researchers from the University of Texas and University of Michigan did a meta-analysis of five decades of research involving more than 160,000 children.
They found that spanking usually "does the opposite" of what parents intend it to do and increases the likelihood of "undesired outcomes", such as uncooperative behaviour.
"We found that spanking was associated with unintended detrimental outcomes and was not associated with more immediate or long-term compliance, which are parents’ intended outcomes when they discipline their children," said author Elizabeth Gershoff, associate professor at the University of Texas at Austin.
In the study, published in the Journal of Family Psychology, the researchers defined "spanking" as an "open-handed hit on the behind or extremities".
Current UK law states, mild smacking is permitted as a "reasonable chastisement" providing it does not leave a mark or bruise.
Yet, researchers involved in the study said spanking usually does "more harm than good".
"We as a society think of spanking and physical abuse as distinct behaviours,” Gershoff continued.
"Yet our research shows that spanking is linked with the same negative child outcomes as abuse, just to a slightly lesser degree.”
A spokesman for the NSPCC told the Telegraph: "Children should have the same legal protection from assault as adults do.
"Other research has shown that smacking young children affects their behaviour and mental development, and makes them more likely to be anti-social."