Children as young as five use social media, despite most platforms having rules users must be over the age of 13.

An annual study into media habits, from Ofcom, highlighted the mini social-media mavens, with a third of parents of five- to seven-year-olds revealing their child had a social-media profile.

Among the eight- to 11-year-olds who used social media, the most popular platform was TikTok, with one in every three having an account.

TikTok is a "strictly a 13+ platform".

A spokesman for the viral video-sharing platform said: "We have processes in place to enforce our minimum-age requirements, both at the point of sign-up and through the continuous proactive removal of suspected under-age accounts from the platform.

"Nothing is more important to us than the safety of our community, especially young people."

'Really striking'

The report noted even younger children - TikTots as Ofcom dubbed them - were watching videos on TikTok, including 16% of the three- to four-year-olds.

But this could be children being shown videos by a parent or other older person and does not imply they have own accounts.

Ofcom strategy and research director Yih-Choung Teh said the findings were "really striking".

"I have an 11-year-old and an eight-year-old," he said, "60% of their peers have a social-media profile, which I find a bit surprising.

"Big-tech platforms set minimum ages in their terms and conditions - but it does seem that they aren't really being enforced."

But Mr Teh also said parents had to be aware of what their children were doing online.

"It's not always very easy to tell what they're watching and I think, as a parent, we have responsibilities to have a good dialogue with our kids about what they are doing," he said.

But the survey also found 22% of parents of three- to four year-olds and 38% of parents of eight- to 11-year-olds said they would allow their child to have a profile on social media before they reached the minimum age.