Online editors and moderators understandably reach for the ‘delete’ key when readers comment on stories about live criminal cases on Facebook and Twitter.

The downside to social media threads, which encourage reader participation and create a buzz around a story, is the risk of a criminal contempt of court charge, which no-one wants to face.

Helpful readers’ comments about a defendant, such as ‘I know that bloke, he lives down the road from me. He’s got form for gbh”, could create a substantial risk of seriously prejudicing a trial.

Because it’s not possible to take down a single comment on a Facebook thread, one offending message means that the whole thread must be taken down.

In 2013 the Attorney General warned about social media sites crossing the line on contempt, and announced that he would issue advisory notes on his website and on twitter, to warn social media users against publishing prejudicial material or posting comments which could create a substantial risk of seriously prejudicing a trial.

However, it seems that newspapers are nowhere near the worst offenders when it comes to alleged crimes on Facebook and Twitter being reported to police.

Complaints to police involving social media have risen by over 700 per cent, according to new figures obtained by the Press Association through a Freedom of Information Act request.

Not all police forces collated the figures where crimes involved Facebook and Twitter sites, but of those that did, 635 people last year faced criminal charges over allegations involving the sites, compared with 46 people in 2008.

Where forces released a detailed breakdown of crime reports, harassment and menacing messages were amongst the most common allegations.

According to the PA report, 38 forces reported a rise in crime reports on Facebook, and 24 forces had received more Twitter crime reports than the previous year. In 2014 there were 4,908 reports in which the two sites were a factor.

The forces don’t specify what role the social media sites played in the crime itself. The offences may have involved posting offensive or abusive messages or pornography on the sites, or have been used as a tool to commit an offence, or simply been mentioned in the crime report.

The Metropolitan Police received 1,207 crime reports mentioning Facebook last year, (up from 935 in 2013) and 138 reports which mentioned Twitter, (up from 105 in 2013).

In Greater Manchester, Facebook appeared in 959 crime reports last year, up from 512 in 2013.

Andy Trotter of the Association of Chief Police Officers has said that the figures demonstrated a new challenge, but that the police needed to differentiate between obnoxious and disagreeable messages and the ‘higher end’ of offending, where forces needed to get involved.

Online editors and mediators are asked to make a similar distinction between user generated content which risks breaching their house rules on those which break the law.

Remember, cases are live for contempt purposes from the moment a suspect is arrested.

It is crucial that editors carry out a proper assessment of whether a tweet or a Facebook comment creates a substantial risk of serious prejudice. It is no defence to have tweeted or posted the offending message without intending to prejudice a trial.