A threefold increase in the number of South Australian children charged with child pornography offences has prompted the state attorney general John Rau to seek a national response to what he believes could be the cause: a rise in sexting between teenagers and children.

Since 2009, the number of children under 18 charged with child pornography offences in South Australia has risen from 15 per year to 44. A further breakdown of the data is not available but Rau and South Australian police believe it may be linked to an anecdotal rise in sexting – sending explicit images via phone – among children.

Under current South Australian law, children can be convicted and placed on the child sex offenders register, although the attorney’s general office said this has not yet happened.

“It would have an impact on the nature of their employment, ability to travel, as well as where they could reside and who they could associate with,” Rau told Guardian Australia, adding that a judge may find it necessary in some cases.

Rau is calling for a multi-government response, including education campaigns targeted at parents and children, and has written to his interstate and federal counterparts encouraging them to address the issue at the next state and territory attorneys-general meeting.

“Ideally, a national approach to this issue would be preferred as there are complexities involving telecommunications law which can only be dealt with federally,” he said.

Over recent years, numerous state police forces have issued warnings to teenagers and parents about the potential consequences of sexting – including legal ramifications.

In 2012, WA police warned that children engaging in sexting may be committing an offence under a number of child pornography laws, many of which carry a maximum of 10 years jail. Similar laws are in place in other states.

NSW attorney general Greg Smith told Guardian Australia that he supports Rau’s initiative in raising the issue.

“With the increased use of technology by young people, the practice of sexting anecdotally appears to be widespread,” said Smith.

“In NSW this does not appear to have led to a significant increase in charges, and police retain discretion. However, I would be concerned if there is evidence innocent adolescent behaviour was routinely criminalised, leaving a young person with life-long consequences.”

In NSW, around four people under 18 have been charged with offences relating to child abuse material or child pornography each year since 2009. The charges may be related to a number of criminal acts, including sexting.

In 2010, the state’s Crimes Act was changed so that related crimes are no longer referred to as “child pornography”, as the language was thought to be inaccurate.

“The NSW Crimes Act has been changed to refer to it all as child abuse material. It’s not pornography, it’s a crime,” detective inspector Michael Haddow, manager of the child exploitation internet unit at the NSW police sex crimes squad, told Guardian Australia.

Haddow said young people need to be aware that when they engage in “sexting” they are committing an offence and could be subject to charge, although he believed that would be rare as NSW police have alternative options to deal with young offenders, including cautions and conferencing with police.

“The more important message is that young people need to be aware of this because when you send images of yourself, whether by email or social media, they are out there and out there for good,” said Haddow.

New Victorian laws are expected to come in some time this year after the state government agreed in December to change its legislation and to make non-consensual distribution of explicit images an offence, and to ensure that children would not be charged.

The modifications – a national first – were the result of a parliamentary inquiry into sexting, and give children a defence against charges if they were sexting with someone of no more than two years’ difference in age.

A new summary offence will also be enacted of forwarding an intimate image without consent, which seeks to address incidents of jilted partners forwarding messages in apparent revenge.

Coalition MP Clem Newton-Brown, chair of the Victorian parliament’s law reform committee, told Guardian Australia very few children have been convicted of offences, unless it was warranted by aggravated circumstances.

“The evidence from Victoria was that police were exercising their discretion widely,” he said, however “the committee and now the government thinks that now it’s appropriate there be defences so that children who are caught sexting are not at the mercy of a policeman’s discretion.”

Rau told Guardian Australia he would like to see the outcomes of Victoria’s approach, but “we need to be very careful that any loosening of the legislation does not allow more serious offenders off the hook.”