A 21-year-old man has been arrested in Manchester on suspicion of harassment offences after feminist campaigner Caroline Criado Perez was targeted on Twitter.
Scotland Yard confirmed the arrest is in connection with an allegation of malicious communications received by officers in London on Thursday.
Ms Criado Perez, who successfully campaigned for a woman's picture to be put on a new bank note, has received a deluge of threats from various sources on the microblogging site.
Twitter has faced calls to take faster and stronger action against online abuse in the wake of the incident.
More top news
Sheffield United are close to agreeing a deal to re-sign striker Ched Evans from Chesterfield, ITV News understands.
Cold and unsettled tomorrow with a chilly wind.
Police have released CCTV as they appeal for help in finding a 27-year-old trainee nurse who has been missing since last Thurday.