Two journalists have launched legal action against Twitter and former Sunday Independent columnist Eoghan Harris.
Mr Harris has admitted to being one of a number of contributors to an anonymous Twitter account that directed negative tweets against Irish Examiner journalist Aoife Moore and Belfast Telegraph journalist Allison Morris.
They claim the account, set up under the name Barbara J Pym, directed tweets at Ms Moore over a one-year period and at Ms Morris over “a period of months.”
The legal action on behalf of Ms Moore seeks to compel Twitter to reveal the identities of anyone else who was involved in the account.
Phoenix Law, which represents both women, said Ms Moore was, “subject of an extensive and malicious campaign of online abuse which encompassed in excess of 120 tweets from two accounts in a period short of twelve months.”
It claims the tweets, “sought to belittle her views and undermine her professionalism through the use of misogynistic language.”
"It ends now"
In a statement, Ms Moore said the account’s “obsessive attacks on me have sought to damage my reputation and standing as a journalist among my peers and colleagues.”
“These posts tagged other journalists and politicians spreading dangerous lies about me while I carried out my work professionally and diligently.
“These statements attempted to use my background and hometown against me in a misguided attempt to belittle my work and promote a false narrative.
“It’s been open season on women in media for too long and it ends now.”
"Sustained and obsessive"
The action on behalf of Ms Morris claims she was libelled by the accounts.
It also accuses Mr Harris of using other accounts to direct tweets at Ms Morris. It seeks an injunction requiring him to “disclose all fake accounts” he allegedly used as well as any other individuals that were involved.
Ms Morris said: “The sustained and obsessive attacks on myself by these accounts occurred at a time and in a manner that was clearly designed to damage my professional reputation.”
She claimed the accounts tagged other journalists in the posts in order to spread “these dangerous and defamatory allegations to as wide an audience as possible.”
“As a female journalist and commentator, the posts also had a deeply misogynist tone to them, all too common on social media,” she said.
“Women working in the media are not fair game for those who wish to control every aspect of our profession and dictate who is entitled to a platform.”
Mr Harris has admitted involvement in the Barbara J Pym account but denied that tweets sent from the account abusive or sexist.