TikTok, the wildly popular video app, and its Chinese parent ByteDance could face a damages claim worth billions of dollars in London's High Court over allegations they illegally harvested the private data of millions of European children.

Anne Longfield, the former Children's Commissioner for England and so-called "litigation friend", or public face, of an anonymous 12-year-old girl leading the class action, said on Wednesday that affected children could receive thousands of pounds each if the claim is successful.