Illegal posters put up in London bus shelters declaring Israel a “racist endeavour” have been unanimously condemned by the London Assembly.

On Wednesday, bus stops in at least four different sites across the capital were spotted featuring the statement “Israel is a racist endeavour” - apparently in protest at Labour’s decision to adopt all internationally recognised examples of antisemitism.

The posters were a reference to one of the examples of modern antisemitism as defined by the International Holocaust Remembrance Alliance (IHRA).

Labour’s adoption of the IHRA document came after months of prevarication that threatened to further engulf the party over accusations of deep-rooted antisemitism.

Mr Corbyn, in a rare defeat, was forced to withdraw a clarification, because he lacked support, which argued it should not be “regarded as antisemitic to describe Israel, its policies or the circumstances around its foundation as racist”.

On Thursday, the Assembly passed the motion condemning the posters and thanking London mayor Sadiq Khan for his “swift criticism of this vandalism”. It also urged Transport for London and the police to “ensure that those responsible are identified, found and brought to justice."

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A spokesperson for Mr Khan had earlier branded the adverts “offensive” and “an act of vandalism”, while the Metropolitan Police announced it had launched an investigation.

Gareth Bacon, an assembly member (AM) who proposed the motion said: “Yesterday we saw a concerted effort by racist, antisemitic and politically motivated people to intimidate London’s Jewish communities.

“We must make a clear and united stand when it comes to racism in all forms and make sure that those trying to demonise certain communities in our city are brought to Justice.”

Andrew Dismore AM, who seconded the motion, said the incident was not the first of its kind in London, and that he had raised the issue with TfL “several times before”.

“Those responsible must be identified and prosecuted if this abuse is to be deterred in the future,” he added.

Protests against Labour antisemitism Show all 14 1 /14 Protests against Labour antisemitism Protests against Labour antisemitism Protesters clashed during the demonstration Reuters Protests against Labour antisemitism Members of the Jewish community hold a protest against Labour party leader Jeremy Corbyn and antisemitism in the Labour Party AFP/Getty Protests against Labour antisemitism Protesters hold placards and flags during a demonstration, organised by the British Board of Jewish Deputies for those who oppose antisemitism, in Parliament Square Reuters Protests against Labour antisemitism Hundreds of people gathered in Parliament Square to protest against antisemitism in the Labour Party EPA Protests against Labour antisemitism Labour MP Luciana Berger speaks during the protest PA Protests against Labour antisemitism A protester blows through a shofar during the demonstration Getty Protests against Labour antisemitism Members of London's Jewish community protest in support of Labour leader Jeremy Corbyn outside parliament EPA Protests against Labour antisemitism Labour MP John Mann speaks during a protest against antisemitism PA Protests against Labour antisemitism People protest against antisemitism in the Labour Party as Jewish community leaders have launched a scathing attack on Jeremy Corbyn, claiming he has sided with antisemites ‘again and again’ PA Protests against Labour antisemitism Labour politicians Stella Creasy and Chuka Umunna leave after attending the demonstration Getty Protests against Labour antisemitism A pro-Jeremy Corbyn protester holds a placard during a counter-protest Getty Protests against Labour antisemitism A support of the Labour Party hold up a placard during the demonstration Reuters Protests against Labour antisemitism Jeremy Corbyn supporters during the demo Reuters Protests against Labour antisemitism A protester holds up a sign reading ‘For the many, not the Jew’ AFP

JC Decaux, the advertising firm which owns a number of the advertising spaces, told The Jewish Chronicle the posters were “vandalism – not advertising”, and that it had reported the bus stops in question.