Twitter users claim that their posts are being deleted if they criticise United Airlines.

A range of tweeters claim that their posts about an incident on the airline are being removed without notice and without them being aware of it.

The claims come after United Airlines had a man forcibly removed from a plane, causing him to be carried down the aisle and leave with his face bleeding. The incident has been criticised by customers and much of the world, and United's share price has fallen after the incident.

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Several Twitter users claim that they are seeing posts referencing that incident — for the most part criticising the airline — disappear from their profiles and from people's timelines.

Some even suggested that Twitter was being paid to monitor tweets involving United Airlines and disappear them. Others said that Twitter appeared to be deleting posts that referenced the deletions themselves.

But Twitter isn't thought to remove content, either asking users to delete their tweets if they are in violation of rules, or suspending the users that post them if they refuse to do so. Posting such tweets wouldn't be in violation of Twitter's rules anyway, which allows for criticism of companies so long as that criticism isn't abusive.

Some of the tweets could be being hidden by the site's automatic tools, which are made to spot potential abuse and keep it from spreading around the site. United has received a torrent of criticism since the incident, including some that uses swear words or other words that break Twitter's abuse rules.