A man has been arrested and bailed by police in Bristol in connection with threats made on Twitter.
The man, 32, is suspected of offences against two women, who reported the allegations on 25 and 29 July.
The BBC understands the arrest relates to threats made against Labour MP Stella Creasy and feminist campaigner Caroline Criado-Perez.
The man was bailed to return to a central London police station in late September pending further inquiries.
A number of prominent women have recently been targeted online by anonymous abusers, or so-called "trolls".
This was the third arrest in connection with the Met's investigation into the recent online abuse.
The man was being held under the Protection from Harassment Act 1997, the Metropolitan Police said.
There have been calls for Twitter to do more to prevent abuse after anonymous users of the site sent messages to well-known women threatening bomb and rape attacks.
Female journalists, columnists and the historian Mary Beard were all targeted.
Last weekend some users boycotted the site to protest against trolling - the practice of insulting or intimidating others, usually under a pseudonym, to provoke a reaction.
Twitter attracted media and police attention after campaigner Ms Criado-Perez was targeted by trolls when she successfully lobbied for a woman to be pictured once more on UK banknotes.
A 21-year-old man was arrested in Manchester on 28 July after Ms Criado-Perez reported the abuse to police, while a 25-year-old man was held by Northumbria Police on 30 July in connection with the allegations as well as those against Ms Creasy.
Twitter has drafted in extra staff to deal with the levels of abuse and has moved to clarify its reporting procedures.
Last week the company apologised to the women affected, saying what had happened was "unacceptable".