London (CNN) -- British authorities are investigating after various female journalists got bomb threats via Twitter amid escalating calls for action to prevent abuse against women on social media.
The bomb threats come only days after feminist Caroline Criado-Perez and Labour Party politician Stella Creasy received a barrage of rape threats via Twitter, prompting a wide outcry.
A Metropolitan Police spokesman said Thursday the force had "received a number of allegations relating to threats sent to a number of female journalists on Twitter and inquiries are being made."
No arrests have been made, he said.
Hadley Freeman, a columnist with The Guardian newspaper, was one of the journalists sent the online bomb threat Wednesday by an anonymous Twitter user.
She alerted police after receiving the message, which read: "A BOMB HAS BEEN PLACED OUTSIDE YOUR HOME. IT WILL GO OFF AT 10:47."
"We've gone from rape to bomb threats, I see," she said.
Another tweet by Freeman said, "Thanks all for your concern. The police have been round and are now investigating this 'arrestable offense.' "
Freeman had written a column Tuesday titled "How to use the internet without being a total loser," which looked at online misogyny, abuse and freedom of speech issues.
Another columnist, Grace Dent who writes for The Independent and others, received the same bomb threat via Twitter. She shared a screen grab of the message, saying "Well, this is a new low."
Other women to be sent it include Time magazine's Europe editor, Catherine Mayer, who described it on Twitter as a "Not very credible-sounding bomb threat addressed to me."
Women's editor Emma Barnett of The Telegraph newspaper said she had also received the threat but, rather than report it, had headed to the pub to meet a contact as planned.
Explaining her reaction, she said it was in part due to having had "years of abuse on Twitter and in the comment box beneath my Telegraph articles," and in part a lack of faith in the ability of the police to do anything about it.
The account from which the bomb threats were sent has been suspended.
Arrests after onslaught of rape threats
Criado-Perez, a freelance journalist as well as a feminist campaigner, attracted the attention of Internet "trolls" by petitioning to have women displayed on British banknotes.
Police in Manchester arrested a 21-year-old man Sunday. Criado-Perez contacted police after a daylong onslaught in which she received around 50 sexually abusive tweets an hour.
The feminist champion, whose campaign resulted in the Bank of England agreeing to picture "Pride and Prejudice" author Jane Austen on every 10-pound bill, tweeted throughout the abuse: "I actually can't keep up with the screen-capping & reporting -- rape threats thick and fast now. If anyone wants to report the tweets to Twitter."
Twitter UK's General Manager Tony Wang said the social networking company takes online abuse very seriously, offering to suspend accounts, and called on people to report any "violation of Twitter rules."
Creasy, who represents Walthamstow in east London in Parliament, became the target of online rape threats after she spoke out in support of Criado-Perez.
She tweeted late Sunday: "You send me a rape threat you morons I will report you to the police & ensure action taken."
A 25-year-old man was arrested in northeastern England on Tuesday on suspicion of harassment, the Metropolitan Police said, in connection with "allegations made to police by two separate victims, who made reports of malicious communication to police on 25 and 29 July."
An online petition set up on Change.org calling for Twitter to add a "report abuse" button to tweets has garnered more than 110,000 signatures.
"Abuse on Twitter is common; sadly too common. And it frequently goes ignored," the petition states.
The micro blogging site must recognize that its current reporting system "is below required standards," and do more to protect its users, it says.
Vivienne Hayes, chief executive of the London-based Women's Resource Centre, a national umbrella group for women's charities, said the online abuse directed against women is "extremely concerning."
"You have to ask the question, where does this come from ... and why do some people think it's acceptable to do that?" she said.
Hayes suggests that the way that women's worth is commonly assessed in the media by their "physicalness, sexuality and availability to men" is sending the wrong message to men and women.
The Twitter threats are "one of the more serious manifestations of what appears an unacceptable level of women-hating," she said, adding that it points to a society-wide issue that is fairly deep-rooted.
Education is key to changing attitudes and making clear that the denigration of women and violence against them are unacceptable, she said.
"I hope the horrendous level of this kind of trolling is going to push this issue into the forefront" and prompt government action, she said.
CNN's Alexander Felton, Atika Shubert and Oliver Joy contributed to this report.