Chilling scenes of protesters marching unhindered through the capital calling for an “intifada from London to Gaza” and chanting antisemitic slogans have prompted furious accusations that the police are failing doing their job.

An estimated 100,000 people swarmed central London on Saturday to call for a “ceasefire”, with many shouting “From the river to the sea”, a chant often understood to be a call for the destruction of Israel.

Some demonstrators could also be heard singing an ancient Islamic battle-cry against Jews; others handed out pamphlets praising Hamas terrorists.

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A woman attracting the attention of Met officers at the rally (Photo: the Metropolitan Police)

Former Met Police detective Peter Bleksley said: “This is sick behaviour. The Met said they would crack down on this sort of thing and quite simply they haven’t. It’s appalling.”

Conservative MP and former cabinet minister Simon Clarke told The Sun: “We should not have these scenes of hatred and bigotry on our streets.”

Counter-terror officers also told The Times they had concerns about the presence of Iranian operatives being present at protests in order to heighten tensions over Israel’s war with Gaza.

Speaking after a Cobra meeting called by Prime Minister Rishi Sunak on Monday to discuss the “accelerated” threat of terrorism in Britain, Home Secretary Suella Braverman said:

“We’ve seen now tens of thousands of people take to the streets after the massacre of Jewish people… chanting for the erasure of Israel from the map. To my mind there is only one way to describe those marches: they are hate marches.”

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Protesters at the pro-Palestine rally (Photo: Getty Images)

Police were called to investigate pamphlets distributed during the march praising the “extraordinary heroism” of Hamas terrorists.

The literature, which pledges to support Hamas “unconditionally”, was spotted at multiple stalls along the route, including in Parliament Square.

One video showed demonstrators chanting “Khaybar Khaybar, O Jews the army of Mohammed is coming”; a reference to the battle of Khaybar in 628 in which the early Muslims defeated Jewish tribes in Arabia.

One person also appeared to be holding an effigy of a dead baby.

Police issued an appeal for more information on two women over both incidents.

The Met said that officers “were deployed quite quickly to the place where the video was filmed but the two women weren’t there, or could not be found, when they arrived”.

Crossbench peer John Woodcock, the government’s adviser on political violence, told The Sun: “We must bring the perpetrators of this antisemitic crime to book and stand together to drive out the dark stain of Jewish hate that has reached too far into our communities.”

Tory MP Nigel Mills said: “The police should be making a stand and not relying on people on social media to tip them off.”

A Met Police spokesman said: “Officers have made 51 arrests at protests over the past three weekends. We’ve been clear over the last week that wherever possible we will police up to the line of the law.

“There will be some slogans and chants that are obviously lawful or unlawful, but there will be others that are the subject of intense public debate where different groups interpret the language used in different ways. It falls to the police to weigh up all these factors and to reach a clear position on how officers should be directed to respond.”

On the “river to sea” chant, they said: “It is likely that its use in a wider protest setting would not be an offence and would not result in arrests”.