A police force has warned schoolchildren who share so-called "sexts" with friends over the internet that they could face prosecution in the criminal courts.
In a letter sent to schools in Nottinghamshire, the county's sexual exploitation investigation unit said officers were receiving reports on a daily basis of naked images being sent between teenagers using mobile phones.
In one recent case cited in the letter, a teenage girl who sent a topless picture of herself to her boyfriend was investigated after being deemed to have distributed an indecent image of a child.
The girl's boyfriend, who forwarded the image to friends after they split up, is reported to have received a caution.
In the letter sent to school officials, Detective Inspector Martin Hillier warns that court action for such offences may even see a child forced to register as a sex offender.
The officer wrote: "I have grave concerns over the amount of referrals Nottinghamshire Police are receiving on a daily basis in relation to naked images being sent between teenagers via either social networking, texts or mobile phone apps.
"It is crucial that children understand that every internet site and social networking site is monitored by an administrator.
"When photographs that fall within the category of an indecent image [even if taken with consent] are uploaded, reports are made by the administrators to the police.
"If a person is aged over ten years and distributes [shares - even to friends] an indecent image then they can be arrested, charged and dealt with for this offence.
"If they are found guilty they must then register as a sex offender."
Stressing that images are almost impossible to remove from the internet after they have been uploaded, the officer added: "An individual's online reputation needs protecting as it stays with them for the rest of their life.
"I would like to make every school in Nottinghamshire aware of these offences and the implications of pupils' involvement in such behaviour."
A "sext" is defined as a self-generated explicit image which is sent to other people by phone or over the internet.
In January this year, Nottinghamshire County Council's anti-bullying co-ordinator Lorna Naylor warned youngsters that such images could leave them open to blackmail.
Ms Naylor said: "They can be deleted on social media or may only last a few seconds on apps like Snapchat, but images can still be saved or copied by others.
"These images may never be completely removed and could be found in the future, for example when applying for jobs or university.
"Young people may think 'sexting' is harmless but it can leave them vulnerable to blackmail where someone may threaten to share the pictures with family and friends unless they send money or more images."