Holocaust denial should be covered by free speech guarantees, an activist told a Labour Party conference fringe event on Monday as another called for Jewish and pro-Israel groups to be expelled from the party.

Israeli-American author Miko Peled reportedly said Labour members should support the freedom to “discuss every issue, whether it’s the holocaust, yes or no, whether it’s Palestine liberation – the entire spectrum.”

“There should be no limits on the discussion,” he added before advancing other untested assertions about the Jewish State that included calling it an “apartheid” regime.

Peled attacked the spending power of “the Zionists”, suggested that “every person standing for city council in America gets a five star trip to Israel, all expenses paid” while “Billions” are spent as part of a secret global campaign to “silence the Palestinian voice.”

He concluded by offering that the Jewish state was “a racist and colonialist project” whose edifice was “crumbling”.

The Free Speech on Israel (FSOI) event took place outside the main Labour conference venue but was listed in its official handbook. It was headlined: ‘Free speech on Israel: why we oppose the witch hunt.’ Attendees were warned, without apparent irony, not to record or tweet or post to public media anything discussed to a wider public audience, the Daily Mail reports.

Leaflets handed out at the event branded claims of growing anti-Semitism in the UK “hysterical” and a “manufactured moral panic.”

Several attendees also said claims of anti-Semitism in the Labour Party were part of a plot by the pro-Israel lobby and the Labour right to stop Jeremy Corbyn from becoming prime minister, according to the Daily Mirror. Others spoke up in favour of former London mayor Ken Livingstone who remains suspended from the party for claiming that Hitler supported Zionism.

A call from Michael Kalmanovitz, of the “International Jewish Anti-Zionist Network” for the Jewish Labour Movement and the Labour Friends of Israel to be expelled from the Labour Party was met by applause. “What are JM and LFI doing in our Party?” he asked. “It’s time we campaigned to kick them out.”

Last year, an internal inquiry was carried out into claims of anti-Semitism in the Labour Party following the suspension of MP Naz Shah and Ken Livingstone.

It found there was evidence of “ignorant attitudes” but that the “Labour Party is not overrun by anti-Semitism, Islamophobia, or other forms of racism”.

Labour’s deputy leader, Tom Watson, said the party would now investigate how it gave a platform at a conference fringe event to a speaker who said people should be allowed to question whether the Holocaust happened.

Watson said he was disgusted by the remarks and said Peled should be expelled from the party, if he was a member.

“It is nothing to do with the official Labour party conference. And if there was Holocaust denial there, these people have no right to be in the Labour party, and if they are they should be expelled,” he told ITV’s Good Morning Britain.