The British MP Stella Creasy, who has spoken out about the death and rape threats she has received on Twitter, has been tweeted a photograph of a masked man brandishing a knife, as the campaign of attacks on women who highlight online abuse continues.

The Twitter user, operating under the name @Murkztah_, stated: "I'm gonna be the first thing u see when u wake up."

The latest threat comes after a series of women in the public eye exposed the threats of violence they were subjected to on the social networking site, which has called the abuse unacceptable, clarified its rules on abusive behaviour and put extra staff in place to handle abuse reports.

The Twitter user who targeted Creasy has been banned from the site and reported to police.

The Labour MP has received a number of threats which she has made public. One user, calling himself @killcreasynow, threatened the Walthamstow MP with sexual violence and threatened to behead her. After the user was suspended by the site, another account, called @eatcreasynow, stated: "HI AGAIN S***!! IT TOOK TWITTER 30 MINUTES TO BAN ME BEFORE … I AM HERE AGAIN TO TELL YOU I WILL RAPE YOU TOMORROW AT 6PM."

On Monday it emerged that the journalists India Knight and Laurie Penny had received bomb threats after similar tweets were sent to the campaigner and writer Caroline Criado-Perez and the historian Mary Beard.

Penny, who expressed her frustration at having to waste part of her working day reporting the threat, tweeted a screenshot of it and later told followers: "Police are here now and being very helpful. Am being advised to stay elsewhere tonight; have already sorted that out."

Knight meanwhile tweeted: "Very grateful to @metpoliceuk, but officers wouldn't have to waste their time if @twitter could deal w this crap."

Beard, who contacted police on Sunday after receiving a message claiming a bomb had been left outside her home, told BBC Breakfast on Monday that she has since received further threats on Twitter claiming that the originals were "just a practice run".

The Guardian columnist Hadley Freeman, the Independent columnist Grace Dent and the Europe editor of Time magazine, Catherine Mayer, as well as a number of other women, have previously said they had been the subject of bomb threats on the site, while a number have received threats of rape.

Beard said: "I've had lots of abuse, but only recently have I had these things actually threatening violence rape and death.

"I think we've got to be quite careful about drawing a distinction between those things because abuse is very nasty, it's sexist, it's misogynist but I think in some ways you can cope with that by naming and shaming.

"That's what I have quite often done – earlier this week I retweeted one lad's Twitter threat and someone threatened to tell his mum and that sort of solved it.

"I think you have to be absolutely clear that these threats that have been coming to me and to other women and also, I have to say, to women who aren't lucky or unlucky enough to be in the public eye – these are criminal threats, they are threats of violence and death and all you can do is take them to the police.

"There is no two ways about it, threatening to kill someone is a crime and that's what I and other people have done and I hope other women who get these threats will do the same."

Beard said that although Twitter had been slow off the mark to address the issue, she was happy with the support she had received from the site in the past 24 hours.

Tony Wang, Twitter's UK general manager, posted a series of tweets on Monday saying abuse was "simply not acceptable". His messages came after the website clarified its rules on abusive behaviour and put extra staff in place to handle reports of abuse.

Scotland Yard said it had launched an investigation into eight allegations of online abuse and threats. "The police central e-crime unit (PCeU), who hold the police national cybercrime remit, is now investigating allegations made by eight people that they have been subject to harassment, malicious communication or bomb threats," the Met said.