Relatives who “iron” a young girl’s chest with a hot stone or other objects to delay breast formation could face up to 10 years in prison, under new guidance published by the Crown Prosecution Service.

The guidance makes clear to police and prosecutors that breast-ironing, a ritual common in parts of Africa that now sometimes happens in the UK, is a crime that can be charged under existing law even if the victim is said to have consented.

In January the Guardian revealed anecdotal evidence of dozens of British cases of the practice, in which a girl’s chest is “ironed” with a hot stone to delay breast formation, thereby supposedly protecting them from unwanted male attention. The government issued a statement promising to tackle the practice, which it described as child abuse.

“The message that we have is quite clear – breast-ironing is child abuse,” said Jaswant Narwal, a chief prosecutor who specialises in so-called “honour” abuse. “What we want is for these practices not to happen, because these are essentially criminal offences,” she told the Guardian.

While the move does not change the law to make breast-ironing a specific offence, the CPS said it hoped the guidance would provide reassurance to victims and a warning to perpetrators. “We hope this new guidance will give victims, police and prosecutors the confidence they need to bring perpetrators of this cruelty to justice,” Narwal said.

She said victims may be dissuaded from turning to the police because the practice may occur in the family home, where the perpetrator could be the victim’s own mother.

“Another reason is that they may not understand or believe that a crime has indeed been committed. That’s why this guidance is important - because it’s going to go someway to confirm the legal position … so that we can have some viable cases coming forward for prosecution.”

In March the National Education Union said breast-ironing awareness should be made part of the mandatory school curriculum to protect young girls from abuse.

Alex Carlile, a QC and peer who in January tabled questions in parliament concerning the practice, said the CPS guidance was “a welcome step forward”. “It is a clear warning that breast-ironing gives rise to a serious criminal charge. Those who do it are likely to be jailed,” he said.

Comfort, a woman who has spoken out about undergoing breast-ironing as a nine-year-old, said: “It’s a start at least. Now those [affected] children will know that the police are aware of it, that it’s nothing new … so that it doesn’t sound like they are talking about something foreign. And even the children themselves will now know that if there’s guidance, it’s serious – it’s a crime.”

Leyla Hussein, a British-Somali anti-FGM campaigner and psychotherapist, said prosecuting cases of breast-ironing under existing legislation was better than having a separate law, as is the case with female genital mutilation (FGM).

“Abuse is abuse,” she said. “We are not going to have a separate law if people started cutting hands or fingers. We got that so wrong when it came to FGM.”

Narwal stressed that the new guidance was not about criminalising families for their cultural practices. “It’s not a new law – it’s existing legislation. We respect families and we respect cultures. But where actual harm is being caused to children, that’s where it can be considered to be a criminal offence.”

Activistsestimate that at least 1,000 women and girls have been subjected to the abuse in the UK, but there has been no formal assessment of the prevalence of breast-ironing in the country.