The veteran left-wing activist Tariq Ali has insisted the Israeli government was to blame for the recent rise in antisemitism.

In a speech at a pro-Palestinian rally outside Downing Street in response to the violence on the border of Gaza, he attacked what he claimed was a “vile and grotesque” campaign against Labour leader Jeremy Corbyn.

Describing Mr Corbyn as his “old friend and comrade”, Mr Ali – who founded the Stop The War movement – said that he wanted to begin his remarks by speaking about “antisemitism that we are told has swept the Labour Party, that we are told is a big problem for the left.”

He accepted there was prejudice against Muslim, Jew and gay people, but added: “If you were to ask me what is a bigger problem in Europe and north America – is it antisemitism, or is it Islamophobia?

“The answer is very clear, it is Islamophobia.”

Mr Ali said the attacks on Jeremy Corbyn were “disgusting” but were targeted at him because he broke the mould on attitudes to Britain’s foreign policy and was an anti-war politician.

“I predict this vile, grotesque campaign charging him of being soft on antisemitism will collapse. It’s already on the retreat. People don’t believe it.”

On Israel, Mr Ali said: “Many people deep down in their hearts may be scared to say it in public given the strange atmosphere that exists, but it needs to be said.

“The purveyors of antisemitism today, those who have encouraged antisemitism are the Israeli government.

“Killing Palestinians the way that they do it, targeting children as they have done; this is what produces a crude form of antisemitism.

“And the support given to this by right-wing Zionist organisations in Europe and America doesn’t help challenging antisemitism either.”

The demonstration on Saturday was organised by the Friends of Al-Aqsa, Palestine Solidarity Campaign, Palestinian Forum in Britain and Stop the War.

A message was read out from Mr Corbyn condemning the deaths of Palestinian protestors on the Gaza border as an “outrage”.