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
New research calls into question certain common, private treatments whose costs can run into the thousands.
1,209 people were found guilty of 'trolling' offences in 2014 - and 155 have been jailed.
Critics are ambivalent to this year's slate of winners, who were picked in part by American directors Joel and Ethan Coen.