A 32-year-old man has been arrested in Bristol in connection to allegations of threats against Stella Creasy and Caroline Criado-Perez on Twitter.
The arrest comes amid a continued row over Twitter's responsibility to protect its female users from violent misogynistic abuse on the social media site.
"Detectives from the MPS [Metropolitan police service] have this morning, 7 August, arrested a 32-year-old-man, on suspicion of committing an offence under the Protection of Harassment Act, 1997," Scotland Yard said in a statement.
"He was arrested at an address in Bristol by officers from the MPS police central e-crime unit as part of an ongoing investigation into allegations relating to threats made on Twitter."
The arrest was in connection with allegations made on the 25th and 29th of July.
Twitter has pledged to introduce an in-tweet 'report abuse' button to its desktop and Android services, to compliment similar measures on iPhone.
Others have suggested the site eradicate anonymous accounts or introduce a small membership fee.
But critics say the solutions would be an unacceptable limitation on the micro-blogging site.
The arrest comes amid a media backlash against website Ask.fm, which allows anonymous users to ask an individual questions online.
Hannah Smith, a teenager from Leicestershire who was relentlessly bullied on the site, was found hanged on Friday.