Davina McCall has issued a stark warning over an "explicit" site on which her teenage daughter was sent X-rated pictures.
She said Tilly, 16, went on Omegle, a chat site for strangers, and within minutes the schoolgirl was sent images of themselves performing sex acts.
The former Big Brother presenter, who is also mum to Holly, 18, and Chester, 13, with her ex husband Matthew Robertson, called Omegle "the most dangerous site I have ever seen".
Davina, 52, told The Sun : "If you are a parent and you have children under the age of 16 you need to be checking their computers that they are not going on Omegle because this is the most dangerous site I have ever seen."
She added: "Tilly showed it to me, I sat down off camera, she was on camera - out of the five people that she had, bearing in mind it's 10 o'clock in the morning, two of them were just pictures of men's groins, with a s****y, w***ing.
"It was the most explicit, horrific thing I have ever... I was like, 'oh my god.'"
Omegle describes itself as a "great way to meet new friends".
But it admits that "predators have been known to use Omegle, so please be careful".
Users must be 18 or over, or 13 and over if they have a parent or guardian's permission.
The small print at the bottom of the homepage reads: "Omegle video chat is moderated. However, moderation is not perfect.
"You may still encounter people who misbehave. They are solely responsible for their own behaviour."
Thames Valley Police issued a warning about Omegle last month.
The force said: "Chatting to different people online can be fun, but as Omegle acknowledges, there is a strong risk of users encountering sexual content on Omegle.
"This is not limited to viewing adult sexual content but could also be young people performing sexual acts or exposing themselves.
"Talk to your child about the dangers of giving out personal information such as their age, their location or their full name to people that they don’t know."
