An internet troll who sent antisemitic messages to a Labour MP and other victims has been jailed for more than two years.

John Nimmo sent messages to Luciana Berger, the Liverpool Wavertree MP, which included a picture of a knife and a threat that she would “get it like Jo Cox”. He referred to Berger as “Jewish scum” and signed off his messages with the words “your friend the Nazi”.

Berger, who has repeatedly suffered racist and antisemitic taunts online, told the court in a statement that the threats from Nimmo had caused her “great fear and anguish”.

She said: “I have had antisemitic messages before, but this time they were alongside references to my colleague Jo Cox. This incident has impacted on me, for all I knew the offender could have been residing next door to me. This caused me to feel physically sick.”

Nimmo has a history of online abuse of women. He has previously been jailed for online harrassment and threats to the Labour MP Stella Creasy and feminist campaigner Caroline Criado-Perez.

At Newcastle crown court on Friday he was sentenced to 27 months in jail after pleading guilty to nine charges; four of sending a communication conveying a grossly offensive message, three of conveying a threatening message and two of sending a communication conveying false information.

Luciana Berger: ‘This caused me to feel physically sick.’ Photograph: Dominic Lipinski/PA

The Crown Prosecution Service successfully argued for an increase in the sentence, which could be applied because some of the offending was motivated by racism.

Judge Robert Adams said Nimmo, who created fake accounts on Twitter to send abusive messages during an 18-month campaign against his victims, was responsible for “cowardly” armchair attacks on the MP and other victims.

Adams said the attack on the MP was the most serious of Nimmo’s offences, coming soon after Cox’s murder last year.

Berger, a former shadow health minister, received Nimmo’s online threat shortly after finishing her regular Friday afternoon MP’s surgery on 8 July. In the note, Nimmo included a photograph of a large kitchen knife, with a warning: “You better watch your back Jewish scum.”

The judge said the threats to the MP contained “significant echoes” of what had happened to Cox and must have been terrifying for Berger.

“You caused terror and paranoia,” he told Nimmo. “You attacked people who were helping society in a variety of different ways.

“The offences were carried out from the comfort of your own home, where you thought you would never be identified while causing misery to other people.”

In separate campaigns, the 28-year-old sent emails to Faith Matters, an anti-hate crime organisation, and threatened to blow up a mosque.

In a long-lasting campaign against another female victim, he branded her a “danger to children” and publicly accused her of being part of a paedophile ring. The victim, who worked with offenders, was left living in fear for herself and her family.

She told police: “I didn’t know what John Nimmo would do next. I have never encountered such an evil person in my life.”

Vic Laffey, defending, said Nimmo, who has Asperger syndrome, led an isolated existence and that the internet had enabled him to say things which would never be said face to face.

The judge increased the sentence by 50% for each of the offences which were motivated by racism. John Dilworth, from the CPS, said: “Nimmo conducted an online campaign of hate-filled abuse in the belief his identity was securely hidden behind the fake accounts he had created.

“However there was a clear forensic link between the messages sent and the device used to send them.”

Berger who has repeatedly been targeted by antisemitic abuse online, told the Guardian she felt Twitter did not do enough to combat abuse.

“I have heard them say for more than two years they are working on these product changes to tackle this,” she said. “It is ridiculous. Where are they? I have had numerous conversations with Twitter about this.

“I have said to Twitter: ‘There is no point [in] me reporting it, because you never take it down.’”

A Twitter spokesman has said the company accepted it had not done enough, and was toughening up its conduct policy.

In a statement after the sentencing, Berger said: “I hope that if any good at all can come from this traumatic experience, it is that others will see that you do not have to suffer in silence. Action will be taken.

“I would encourage anyone affected to report these crimes. Together, we can stand up to and defeat the racists in our communities.”