The child protection charity the NSPCC has said it has been contacted about more than one "vile" Twitter accounts with "disturbing imaged of children."
It has said police are "taking urgent action":
People have expressed concern about a twitter feed with disturbing images of children. We've alerted CEOP. They are looking at it urgently.
Thanks all for raising concerns. We are aware there is more than 1 account. And we will of course be talking to twitter about this.
We share people's concerns about twitter today. Very disturbing. Police taking urgent action. And we will follow up with twitter.
More top news
The Kilauea volcano's eruption has destroyed 40 buildings and forced more than 2,000 people to flee their homes.
M&S has released an initial list of either definite or proposed store closures as it looks to shut over 100 stores by 2022.
Thousands got tattoos of the Manchester bee as a sign of solidarity after the attack, with their impact going beyond ink on their skin.