Twitter is to introduce new restrictions on hateful and pornographic imagery as part of new plans to tackle abuse on the social media site.
A leaked email to the site's Trust and Safety Council published by Wired - which Twitter has confirmed is accurate - said the company would immediately and permanently suspend accounts identified as the source of nude imagery taken without consent.
Hate symbols and other hateful imagery will also now be treated as sensitive media, with the content then hidden behind warning alerts.
"Although we planned on sharing these updates later this week, we hope our approach and upcoming changes, as well as our collaboration with the Trust and Safety Council, show how seriously we are rethinking our rules and how quickly we're moving to update our policies and how we enforce them," a Twitter spokesman told the Press Association.
The Council is made up of 50 independent organisations and charities Twitter consults with on matters of user safety.
The new rules also include an expanded definition of non-consensual nudity, which now constitutes hidden camera content, "creep shots" and "upskirt" photos captured without consent.
Twitter said it would take "enforcement action" against any account found to be the source of such material.
Action may also be taken against unwanted sexual advances, with reports now possible by those who observe it as well as receive it.
Twitter chief executive Jack Dorsey said last week that the firm was planning to announce a "more aggressive stance" on tackling online abuse after the site was criticised for temporarily suspending the account of actress Rose McGowan, who had made accusations against Hollywood producer Harvey Weinstein.
Twitter also said it would take steps to do a "better job of explaining our policies and setting expectations for acceptable behaviour on our service".
The email revealed plans to introduce a new standalone Help Centre web page to explain the site's enforcement decisions and to describe policies in more detail.
The social media giant, along with other tech giants such as Facebook and Google, has previously been urged by the Government to do more to tackle abusive, hateful and extremist content that appears on their platforms.