Twitter is enforcing new rules on abuse from today, aimed at reducing hateful content on the social media platform.
The new guidelines covering abuse, hateful conduct, violence and physical harm were announced last month.
A new rule regarding violence will also take into account activity offline – forbidding users from affiliating with organisations that promote violence against civilians either either on or off Twitter.
Breach of any of the new rules may lead to permanent account suspension, the firm said.
Twitter has reviewing its policies in recent weeks following repeated criticism over how it handles abusive content.
Last month the site paused its verification process, as well as removing verified 'blue tick' badges from right-wing figures, including former English Defence League (EDL) leader Tommy Robinson.
This came after it was criticised for verifying the account of Jason Kessler, a prominent alt-right figure in the US who organised a white nationalist rally in Charlottesville, Virginia.
Twitter said the verified badge was never meant as a sign of endorsement, and the company's boss Jack Dorsey described the process as "broken".
The firm was also recently accused of failing to act on anti-Muslim videos retweeted by US President Donald Trump because the incident made global headlines.
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The site was forced to clarify its position after an it initially appeared to suggest the videos, retweeted by Mr Trump from the account of Britain First deputy leader Jayda Fransen, were not removed because they stoked debate.
Mr Dorsey said the site had "mistakenly pointed to the wrong reason" the videos remained online, with the company adding its current media policy had not been violated, but would "continue to re-evaluate and examine our policies as
the world around us evolves".