Britain's health minister, Jeremy Hunt, threatened to impose new regulations on social media firms unless they do more to protect young people using their services.
Hunt said the groups were "turning a blind eye" to the effect social media had on children's well-being — an accusation that comes as Facebook and others face heightened scrutiny worldwide over their impact and influence.
Google's U.K. operation and Facebook said they were committed to protecting children and working on new features to help. There was no immediate comment from Twitter, Snapchat and other firms.