Twitter is removing tweets hoping for the demise of US President Donald Trump -- a move which opened up the social platform to criticism that it should enforce the same policy for everyone.

San Francisco-based Twitter drew a line on caustic commentary after Trump's Covid-19 hospitalization Friday, telling users that expressing hope for the death of anyone violates policies against abusive behaviour at the one-to-many messaging service.

"Tweets that wish or hope for death, serious bodily harm or fatal disease against anyone are not allowed and will need to be removed," Twitter said in a post.

Attached was a link to a Twitter policy page that said it does not tolerate content that wishes, hopes, or expresses desire for someone to die or contract a fatal disease.

The post sparked a firestorm of responses from people contending that Twitter has not been consistent about enforcing those rules.

"So... you mean to tell us you could've done this the whole time?" Democratic Representative Alexandria Ocasio-Cortez of New York said in a retweet of Twitter's message.

Conservative Republicans have relentless used social media to spew venom at Ocasio-Cortez, often referred to by her initials AOC.

Fellow Democratic lawmaker Rashida Tlaib chimed in with a similar comment, tweeting, "this is messed up. The death threats towards us should have been taking more seriously."

Twitter responded with a pledge to be more even-handed.

"We hear the voices who feel that we're enforcing some policies inconsistently," Twitter said in response to fierce backlash.

"We agree we must do better, and we are working together inside to do so."

Trump's hospitalization for treatment of Covid-19 has been a hot topic on Twitter, with users keen to point out his history of downplaying pandemic risks and safety precautions such as wearing masks.