UNRULY children may be learning their bad behaviour from television adverts and programmes like South Park, a new report has claimed.

Commercials which feature practical jokes, bullying, and ''undesirable'' role models could be causing copycat behaviour, encouraging children to challenge authority from a younger age.

The Independent Television Commission said it was hard to name one particular advert which had produced bad behaviour, but said certain themes were more likely to encourage children to imitate them.

Adverts which show ''wicked or forbidden things'' and ''participants getting away with it'' were highlighted as having the greatest cause for concern.

The ITC refused to single out one particular advert as having a bad influence, but possible candidates would include an advert for Chupa Chups lollipops, which was banned by the television watchdog last month.

The advert featured a man who stamped on a woman's foot, then stole a lollipop out of her mouth when she called out. The ITC said there was a risk the advert could ''directly trigger child emulation''.

Other controversial adverts have included one for an energy drink which showed footballer-turned-actor Vinnie Jones encouraging a robin to fly into a window, and an advert for fizzy drink Tango, which showed a man being shouted at by a gang using loudhailers. It was taken off the air in 1992.

Parents said television programmes like South Park, Power Rangers and WWF Wrestling continued to have the worst influence on their children's behaviour, but adverts were thought to be having an increasing impact because children saw them ''again and again''.

Adults who worked with youngsters said they had noticed an ''increased confidence in challenging authority'' from an earlier

age.

Television was thought to be partly responsible for that, although the report found that the greatest influence continued to come from parents, friends, siblings, and teachers.

ITC director of advertising Stephen Locke said: ''Viewers contact the ITC regularly, concerned that particular ads might have a negative effect on children seeing them.

''Children learn by copying what they see and most of the time that's healthy and positive. But very occasionally they copy something harmful in a commercial. After all,

they see them again and again.''

When the advert for Chupa Chups lollipops was banned last month, the ITC said it could encourage violent copycat behaviour in the playground. It also expressed concern about the advert's portrayal of violence against women and theft, which it said were harmful for both adults and children.

The ITC also banned an advert for the controversial Jim Carrey film, Me Myself and Irene, last month because it referred to a mentally ill character as a ''schizo''.

The ITC said the black comedy's use of the term could ''not be condoned'' and ''could be offensive to those who either suffer from or are related to or work with those who suffer from some form of schizophrenia.''

A recent advert for paint, which showed a woman cutting a swatch of fabric

from a man's jacket, has

also been criticised by

teachers who claim the incident has been copied in playgrounds, and ''Wassup'', the popular saying used by children, has come from a Budweiser ad.

Mr Locke added: ''This research gives us, and all involved in TV advertising, greater knowledge about what might make children copy behaviour. These results help provide guidance to ensure that children continue to be properly protected in the future.''