Twitter admits far more Russian bots posted on election than it had disclosed

Company says it removed more than 50,000 accounts and reported them to investigators, marking latest upward revision of figures

Twitter has admitted that more than 50,000 Russia-linked accounts used its service to post automated material about the 2016 US election - a far greater number than previously disclosed.

Announcing the discovery in a post to its website late on Friday, the company said the posts had reached at least 677,775 Americans, all of whom would be receiving a warning by email.