Broadcaster Andrew Neil has warned that rising anti-Semitism on the left is “more dangerous” than on the right as he issued a scathing condemnation of Ken Livingstone.

The This Week presenter told the Holocaust Educational Trust dinner that “knuckle draggers” and Holocaust deniers were more marginalised than when he was growing up. But the changing face of anti-Semitism meant the charity’s work is more crucial than ever.

He said: “What’s surprised me is the new development in this area is the rise of anti-Semitism on the far left. It’s more dangerous than the knuckle dragging right.

“I don’t say anti-Semitism of the left is entirely new. There’s a strain that’s always run through parts of the British intellectual left but I believe it’s on the rise and given far too easy a pass.” It is possible to “get away” with left-wing prejudice in a way that would never be tolerated when emanating from the right.

He pointed to a fringe event at the Labour Party conference where one speaker suggested it should be possible to debate the “Holocaust, yes or no” and, in a reference to the comments of Ken Livingstone that saw him suspended from the party, he insisted there “could be no bigger insult” than linking Zionism and the Nazis. “We know what he was doing,” said Neil “but still he’s regarded as a respectable politician.”

But he didn’t only have words for politicians on the left. The legendary journalist also took aim at Donald Trump, whose reaction to displays of hate in Charlottesville he described as “shaming” America.

“What’s surprised me is the new development in this area is the rise of anti-Semitism on the far left. It’s more dangerous than the knuckle dragging right.

Introduced by survivor Kitty Hart-Moxon, Neil said he travelled 1,000 miles to attend the dinner but would have flown around the world to be there.

A number of “forces” including the rise of authoritarianism and the reluctance of the left to criticise Islamism – which he described as the main source of anti-Semitism today – make the HET’s work more urgent than ever. As, he suggested, was the fact anti-Zionism is “often used as a cover” for anti-Semitism.

“The Trust remind us where anti-Semitism leads, the more we know about it the more we ensure it doesn’t happen again,” he added.

Earlier, the hundreds of guests at the Dorchester rose to their feet to applaud survivor Ben Helfgott as he was presented with a lifetime dedication award by Home Secretary Amber Rudd for his tireless work to pass on the lessons of the Shoah.

“The legacy of my family and millions of others is held in hands of HET. They are custodians of the awesome task to ensure the memories of those murdered are never forgotten.”

A long-time trustee of HET, member of the Holocaust Memorial Foundation and founder of the 45 Aid Society, Helfgott also competed for Britain in weightlifting at the Olympics within five years of his liberation and twice captained the British squad. He was described in a video message by fellow Olympian Greg Rutherford as a “hero”, while HET chief executive Karen Pollock joked he was “the only man in his 80s who still gives me fitness tips”.

Helfgott said he was “very proud” of all the Trust has achieved, adding: “It is vital work and we must never give up. As we oldest survivors pass on we put our trust in you, the next generation, with great confidence and thanks”.

Judge Rob Rinder, who compered the dinner, fought back tears as he told guests he did so in memory of his late grandfather, who survived Theresienstadt. He said: “The legacy of my family and millions of others is held in hands of HET. They are custodians of the awesome task to ensure the memories of those murdered are never forgotten.” The charity’s weapon was “truth” in a world where fake news is increasingly problematic.

Also addressing the gathering was broadcaster Natasha Kaplinsky, who has many hundreds of “privileged hours” taking testimony from survivors as part of her role with the Holocaust Memorial Foundation. She led a silence for the survivors who have passed away in the last year.