Twitter's UK boss has personally apologised to women who have been attacked by "trolls" on the social networking site, vowing to do more to protect people from abuse.
It comes as Scotland Yard said its e-crime unit was looking into claims by eight people of abuse.
Twitter found itself in the spotlight after three female journalists said they had been the subject of bomb threats on the site and two other women - an MP and a campaigner - received threats of rape.
The bomb threat tweet was sent to Guardian columnist Hadley Freeman, Independent columnist Grace Dent and Europe editor of Time magazine Catherine Mayer, as well as a number of other women.
In separate incidents, Labour MP Stella Creasy and campaigner Caroline Criado-Perez, who successfully fought for a woman's face to appear on £10 banknotes, were threatened on Twitter with rape.
Two arrests have already been made in relation to those threats.
Meanwhile, TV classics expert Mary Beard silenced an internet troll after naming and shaming him on the site.
Twitter UK has now clarified its rules on abusive behaviour amid a growing backlash over a series of attacks.
The firm said it was putting extra staff on the teams which handle abuse reports, and an "in-tweet" report button has been added so people can report abusive behaviour directly from a tweet.
The company, which has its European headquarters in Dublin, has recently taken on its first in-house counsel for the region.
It has also started advertising for a legal policy staff member to work on rotating shifts "to provide timely responses to emergency requests from all over the world".
The job description added: "We're a passionate team of intensely motivated, detail-oriented folks, seeking the same to join us!"
The blogging site's policy shift comes after an online petition calling for a "report abuse" button had attracted more than 120,000 signatures.
