Users of the microblogging service complain at apparent censorship as discussion grows around deaths on convoy - but it isn't justified (updated)

The attack by Israel on a flotilla of ships approaching Gaza has, as you'd expect, generated a huge response on social media - and of course Twitter, with its real-time content, was quick to react.

Many users began the morning by tagging their comments about it with "#flotilla" - a "hashtag" which gives a structure to a discussion or emerging event, as you can filter searches in applications such as Tweetdeck so that you only see those with that tag.

But at around 11am, as #flotilla began "trending" - rising to the topmost-used hashtags on the service - it seemed to vanish.

Was this censorship by Twitter? Quite a few asked the question.

Certainly if you went to the standard URL for such a search - http://search.twitter.com/search?q=%23flotilla - you briefly got a result saying "Twitter error".

However if you used the advanced search, you get the results as you'd expect.

What also happened was that people started using a new hashtag: #freedomflotilla. That rapidly trended.

The error in #flotilla search results quickly fixed itself, though. Possibly the rapid rise in the hashtag's visibility tripped an anti-spam filter at Twitter headquarters (where it was 3am in the morning, so we might assume that it's the machines, rather than the people, who are on duty - though then again, knowing the nocturnal habits of programmers, perhaps not).

Update: Mike Butcher at Techcrunch points out that this surely was a case of anti-spam filtering: there had already been a "flotilla" story in the past week - the anniversary of Dunkirk (for non-Britons: a dramatic rescue during the second world war of British and French troops from the Dunkirk beaches by small craft). And Gaza is frequently topical. (Thanks @vensa in the comments.)

So Twitter's anti-spam algorithms - that is, the machines - likely decided that this was a spam attack trying to piggyback on old hashtags, and pushed the "#flotilla" hashtag out of the trending topics. Is it censorship if it's done by machines that think it's spam? Given that "#freedomflotilla" instead rapidly trended, clearly there's no human censorship against the story of the attack being made visible to other Twitter users.

That's why Trendsmap, which is independent of Twitter and from which the screenshot is taken, looks as it does: it reflects what's on Twitter.

Update 2:: Sean Garrett, who handles communications for Twitter, tweeted this morning to say that "We are investigating a technical issue that caused search errors for a short period of time this morning. Twitter facilitates the open exchange of info & opinions -- when that is hampered by a bug, we take it very seriously." The bug has now been fixed, Twitter says.

So: shock as Twitter not being used to censor news. But it does show the enormous sensitivity there now is about Twitter's impartiality that any suggestion that a world event might be pushed out of its "trending topics" (displayed on the right-hand column of every Twitter user's home page) can create such frustration.

It doesn't, of course, help anyone on the convoy that was attacked. But getting information into public hands is a public good. Twitter is coming closer and closer to being viewed as a utility - certainly by those who use it. Perhaps we'd all feel more comfortable if it had a business model that had real, declared profits - because (to answer @Strummer) that would mean you could be confident of unmediated messages from everywhere in the world.