Ruby Begum, 26, became an internet sensation when she was photographed wielding a baton in front of a mob of protesters in September.
Ms Begum was seen wearing a hijab in a defining image of multicultural Britain.
But yesterday it was claimed that before joining London’s Metropolitan Police in 2016 she took to Twitter to abuse Jews and victims of 9/11.
Ms Begum – who works for the Met Taskforce, a specialist unit to tackle public disorder – had reportedly been running an account under the name Ruby Beees since 2012.
She is said to have posted more than 25,000 messages.
It has now been deleted but an audit showed that among references to football, her cat and raising money for charity she frequently used the offensive term “kuffar” – vernacular for non-Muslims. She also described Pakistanis as “*****”.
Ms Begum is also said to have mocked Zionists – as code for Jews.
In 2014 she allegedly wrote: “Kuffar lips have been all over my mug, there is no way I’m using that thing again.”
It is claimed most of her anti-Semitic comments were made in 2014 when Israel launched an attack against the Palestinian militant group Hamas in the Gaza Strip. The conflict claimed more than 2,000 lives, mostly Palestinians.
In a string of tweets, the officer is said to have referred to anti-Semitic comments, calling Israel “dirty” and referring to “scumbags”.
Later that year, she said: “Zionists have no hearts! They’ll get what’s coming to them subhanallah [glory be to God].”
In March 2014, referring to the fierce cricketing rivalry between Pakistan and Bangladesh, Miss Begum tweeted: “I don’t care about cricket, just love this thing between Bengalis and *****.”
And on the 18th anniversary of the twin-towers terror attacks in New York, she is said to have tweeted: “Omg [O my God] it’s 9/11 today? Jokes, I only noticed.”
In 2014 she reportedly wrote: “Must be stupid if you think I’m gonna do two mins silence for 9/11.”
She has been placed on “restricted duties”.
The Met has launched an investigation and referred the matter to the Independent Office for Police Conduct.
A spokesman said: “There is no place within the Met for any racist, homophobic or otherwise hateful attitudes and officers and staff can expect robust action should they be found to hold or express such views.”