An abusive troll has been using promoted tweets, Twitter's paid-for advertising service, to send a string of hateful transphobic messages.
An account called @caitlin_roperr, which was impersonating the feminist activist Caitlin Roper (who tweets as @caitlin_roper), sent the messages on Wednesday. The account was shut down after around an hour.
Roper (the real one) explained to her Twitter followers what had happened.
"If you look at my pinned tweet on my account, you can see that this has happened to me before," Roper told BuzzFeed News.
She added: "As a vocal feminist activist, I've been targeted in various ways, with threats of rape and violence, and by impersonation. Last year a man made a copy of my twitter profile, copying my picture and bio info, and he began tweeting as me offering sex to men on the internet. I wrote about it for The Guardian.
"Last time it took several hours for Twitter to remove the account, after I had sent them a copy of my photo ID. I was relieved that they acted quickly here, I think within about an hour.
"I do have to wonder how it is that this kind of tweet was able to be promoted."
Understandably, people couldn't quite believe what was appearing on their timeline – since you don't have to be following an account to see its promoted tweets.
One 4Chan user is claiming responibility for the tweets and said he bought them using a pre-paid credit card.
The incident led many users to question how such a message was able to be sent as a promoted tweet.
It's not the first time promoted tweets have been used to sent abusive messages.
A spokesperson for Twitter told BuzzFeed News: "Twitter does not allow the promotion of hate content, including hate speech against a group based on sexual orientation or gender identity. Once this instance was flagged, we immediately suspended the account and stopped." It is understood that Twitter, like other companies, has automated filters that are intended to detect such abuse, although they appear to have failed in this instance.