Online grooming: 'The most distressing experience of my life'
Legislation to protect children and young people from being groomed online should be introduced in the new year, according to the NSPCC.
One mother, whose daughter was targeted online aged 11, said their world had been "turned upside down".
The woman, who cannot be identified to protect her daughter, said she thought Cardiff council's social services did not respond quickly enough.
But a council spokeswoman said strict procedures were followed in such cases.
New figures from the NSPCC show an increase of 13% in the number of online sexual grooming crimes in Wales between April 2018 and 2019, compared with the same period a year earlier.
The mother said she found an indecent photo of a man on her daughter's phone in June.
She realised she had been messaging people on an app called Kik.
The girl's mother contacted the police and, after interviewing her daughter at home, officers took her mobile phone and tablet for investigation.
"It was the most distressing experience of my life," her mother told Newyddion 9.
"I felt completely sick and that our world had been turned upside down in a split second."
Because the girl had not given her name, address or age to the man, the case was not considered urgent.
Her mother said: "It seems that only one had had any, what they would call, 'success' with her, where they managed to have a conversation with her and build up a trust with her, to the extent where he ended up sending her indecent images.
"He'd also convinced her to send images of herself.
"I would like to see at least some kind of pamphlet put in place which is kept in mobile phone shops, doctors' surgeries, hospital waiting rooms, which is a guide on how to set up a child's phone with parental settings, child tariffs, useful apps to stop them taking indecent images.
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"It's definitely had a negative impact on her home life," she said.
"Thankfully, it doesn't seem to have affected her education but she is quite volatile at home and it can be quite hard to comfort her."
More than 7,500 crimes have been recorded in Wales and England since the new offence of sexual communication with a child came into force two years ago.
A freedom of information request from 43 police forces in Wales and England showed one in five victims were aged 11 or under.
The NSPCC said it was calling for legislation to be introduced as soon as possible to protect children.
The UK government has indicated it will publish a draft online harms bill early next year.
The proposals would introduce independent regulation of social networks, with tough sanctions if they fail to keep children safe on their platforms.