Video-sharing app TikTok says it is "sorry" that some children and other young people have felt pressured into sending money to their favourite influencers on the app.
TikTok lets fans send their favourite videomakers "digital gifts", which can cost up to £48.99.A BBC investigation found influencers promising to share their phone numbers with fans in exchange for the gifts.
TikTok said it would strengthen its policies and guidelines but did not explain exactly how.
Claire (not her real name) told BBC News she regretted spending £100 to obtain her favourite TikTok star's phone number - and he had never answered his phone.
Claire, 12, who lives in the north-west of England, sent TikTok star Sebastian Moy a £48.99 "drama queen" gift to show her appreciation for his videos.
And when he had asked for another one in exchange for his personal phone number, she said she was swept up in the moment.
The US-based video-maker has 3.8 million fans on TikTok and has not broken any of the app's rules.He has not responded to the BBC's requests for comment.
Taking a cut
TikTok is the fastest-growing social media app, with about 500 million regular users, although the company doesn't disclose its userbase. It's estimated to have been downloaded more than a billion times on app stores.
The app lets people post 15-second videos. It is known for clips of teenagers lip-syncing and dancing to the latest trending music.
The company says it is most popular with 16- to 24-year-olds but there is evidence that many users are under 13, which is against the app's rules.
The firm has already been fined $5.7m (£4.5m) by a US regulator after being accused of collecting under-13s' personal details without their parents' consent. And on Tuesday, the UK's Information Commissioner revealed she had also launched an inquiry into whether the app was doing enough to safeguard its youngest users.
"We do have an active investigation into TikTok right now, so you can watch that space," said Elizabeth Denham.
Videomakers with more than 1,000 followers are allowed to broadcast live on the platform. It is during these live streams that fans can send digital gifts to show their appreciation.
Gifts appear as on-screen animations and cost between 5p and £48.99. The app's biggest stars can earn thousands of pounds in one live stream.
TikTok declined to say how much of that money it kept - but several influencers told the BBC they took home 50% of all gift revenue earned.