TikTok

Examples include applying bleach to whiten teeth, removing moles at home, and using eyelash glue to make lips appear larger, BBC News has discovered.

When these videos went viral, they encouraged others to copy the so-called "beauty hacks", which could cause permanent harm, the groups warned.

TikTok told BBC News the videos did not violate its community guidelines.

It will store videos, messages and other data generated by European users from the short-form video-sharing app.

Until now all of its users' records were stored in the US, with a back-up copy held in Singapore.

The announcement comes at a time when President Trump has threatened to ban the app in the US on the grounds its Chinese ownership makes it a national security risk.

TikTok's Beijing-based parent company Bytedance denies the charge. However, it is in talks to sell its US, Canada, Australia and New Zealand operations to Microsoft.

About a quarter of those videos were deleted for containing adult nudity or sexual activity, the business said, in its latest transparency report.

The video-sharing app also revealed it had received about 500 requests for data from governments and police, and had complied with about 480 of them.

The US has suggested it is "looking at" whether to ban the Chinese-owned app.

On Monday, US Secretary of State Mike Pompeo suggested that downloading TikTok would put citizens' "private information in the hands of the Chinese Communist Party".

It will let parents link their own TikTok accounts to their child's - and turn features on and off remotely.

That includes a "restricted mode" that tries to filter out inappropriate content, and turning off messaging.

TikTok has an age limit of 13, but many pre-teens still use the Chinese-owned app.

A recent survey by UK media regulator Ofcom found that TikTok was used by 13% of all children aged 12-15 in 2019 - up from 8% the year before.

What does the new feature do?