A man has been arrested over a tweet about the trial of Coronation Street actor Michael Le Vell.
A 43-year-old from Gloucester in England was held on suspicion of revealing the identity of a victim of sex abuse, Greater Manchester Police said.
He has been released on bail.
Superintendent Phil Davies said: "Public identification of victims of sex abuse, in particular child victims engaged in court proceedings, can cause both immediate and long-term distress and harm, especially in cases as serious as this.
"The same principles apply to social media as they do to the mainstream media and we are investigating this matter robustly."
He added: "People may not understand that when they use social media they are required by the law to keep victims anonymous in exactly the same way as people who work in mainstream media.
"The rule of law and consciousness of a sex abuse victim's anonymity should be considered by all who follow these types of cases."
Mr Le Vell, who plays car mechanic Kevin Webster in the ITV1 soap, is on trial at Manchester Crown Court over claims he committed a string of sexual offences against one alleged victim.
He denies the charges.