A mother is urging parents to be vigilant against hidden chat features in online games for children.
Janet Griffiths, from Pontypool, believes her seven-year-old daughter engaged in a conversation with a much older person when playing Roblox.
The person is said to have posed as young boy and asked for her number.
The makers of the game said its messaging facility can be switched off and there is a guide for parents on its website.
Ms Griffiths said her daughter was “quite addicted” to the game.
When she was playing upstairs, Ms Griffiths found her chatting to what her daughter thought was an eight-year-old boy.
Safety features filters out personal information, but the person had requested a phone number by spelling it out in individual messages.
“It was really upsetting,” said Ms Griffiths.
“The way the chat unfolded made me think it was definitely not a child.
“Roblox is targeted at children and it’s not obvious there is a chat facility.”
Tami Bhaumik, vice president of marketing and community safety for Roblox, said: “Roblox is committed to being a leader in protecting the online safety of children and realises that no safety infrastructure is foolproof.
“We are continuously improving our systems and processes and when an incident does occur, we respond quickly.”
Internet safety expert Sangeet Bhullar said parents need to be involved in their children’s online activities.
“It’s one of the key ways that parents can safeguard, educate and be there for their children,” she said.
“Unfortunately it is the case that people try to find their way around the restrictions.”
Ms Bhullar said she did not want to single out Roblox as “unwanted contact can happen even amongst the most popular apps”.
“The broader message is developing young people’s understanding of how to recognise risk online and how to take appropriate actions.”
To mark Safer Internet Day, Children and Social Care Minister Huw Irranca-Davies called on parents to play their role “to ensure their child’s online safety”.