A former aide to Jeremy Corbyn has told a High Court judge that television presenter Rachel Riley was being deliberately provocative when she  “applied” a tweet containing the word Nazi to the then Labour leader two years ago.

Laura Murray, who responded with a tweet describing Ms Riley as “dangerous” and “stupid”, told Mr Justice Nicklin that she had been “shocked and outraged”.

Ms Riley, 35, a numbers expert on the Channel 4 show Countdown, posted a tweet in March 2019 after Mr Corbyn had been hit with an egg while visiting a mosque.

Ms Murray had responded a few hours later, and said nobody should “engage” with the television presenter.

Ms Riley has sued Ms Murray for libel, and says the “dangerous” and “stupid” tweet caused “serious harm” to her reputation.

She says she was being sarcastic in her tweet and had not called Mr Corbyn a Nazi.

Ms Murray, who no longer works in Mr Corbyn’s office, has mounted a defence to Ms Riley’s libel claim.

She says what she tweeted was true, and reflected her honestly held opinions.

Mr Justice Nicklin is overseeing a trial at the High Court in London, which began on Monday and is due to end on Wednesday.

The judge has heard how Ms Riley had initially posted a screenshot of a January 2019 tweet by Guardian columnist Owen Jones, about an attack on former British National Party leader Nick Griffin, which said: “I think sound life advice is, if you don’t want eggs thrown at you, don’t be a Nazi.”

She had added “Good advice”, with emojis of a red rose and an egg.

Later, Ms Murray had tweeted: “Today Jeremy Corbyn went to his local mosque for Visit My Mosque Day, and was attacked by a Brexiteer. Rachel Riley tweets that Corbyn deserves to be violently attacked because he is a Nazi. This woman is as dangerous as she is stupid. Nobody should engage with her. Ever.”

Ms Murray told Mr Justice Nicklin on Tuesday that she thought Ms Riley’s tweet was “deliberately provocative” towards Mr Corbyn.

“It was deliberately provocative and it was designed to provoke a reaction,” said Ms Murray.

“She was getting that reaction.

“A lot of people saying Jeremy Corbyn was not a Nazi.”

Ms Murray added: “The purpose of my tweet was to say to my followers, ‘don’t engage with her. Don’t get embroiled’.”

She said she had read Ms Riley’s tweet as applying the word Nazi to Mr Corbyn.

“That was absolutely 100% how I read it,” she said.

“Owen had tweeted about Nazis being attacked.

“She applied it to Jeremy Corbyn.”

Ms Murray told the judge: “I was just shocked and outraged by her tweet. My intention was to express my outrage.”

Mr Justice Nicklin ruled at an earlier hearing that Ms Murray’s tweet was defamatory.

The judge concluded that the tweet meant that: Ms Riley had “publicly stated” Mr Corbyn had been attacked when visiting a mosque; that he “deserved to be violently attacked”; by doing so, she had shown herself to be a “dangerous and stupid person” who “risked inciting unlawful violence”; and that people should not “engage with her”.

He has now been asked to consider whether serious harm was caused to Ms Riley’s reputation, and whether Ms Murray had a defence of truth, honest opinion or public interest.

Ms Riley, who studied mathematics at Oxford University, has told the judge that she is Jewish and has a “hatred of anti-Semitism”.

She said she spoke out against anti-Semitism and thought the Corbyn-led Labour Party was “fostering anti-Semitism”.

Ms Riley has told the trial that she had been criticised by other Twitter users after posting the “good advice” tweet before Ms Murray joined the discussion.

She said she believed that Ms Murray was blowing a “dog whistle”.