Labour’s adoption of a new rule aimed at taking a tougher approach to combatting antisemitism has received a cautious welcome from Jewish groups after an acrimonious party conference.

Under the rule, the expression of antisemitic views — along with other forms of hate speech such as Islamophobia, sexism and homophobia — will lead to expulsion from the party.

But a series of antisemitic comments and clashes over Israel and the role of Jewish activists within the Labour Party left some Jewish delegates feeling too scared to attend conference sessions.

Others criticised the position of the Jewish Labour Movement, which proposed the new rule.

The group said it had secured a “decisive political victory”, but  one Labour MP described JLM as “Corbyn’s useful idiots”, saying it had been “played” by the Labour leadership so that it could now portray the party’s official Jewish group as supporting Mr Corbyn.

A leading Jewish Labour figure said the rule change was a “double-edged sword” — while it had strengthened JLM’s “legitimacy”, the “long-term trajectory is difficult”.

There was particular anger over a leaflet published by the JLM on the eve of the vote which asked supporters to “help Jeremy Corbyn fight antisemitism”. It came as key allies of Mr Corbyn repeated their claim that allegations of Jew-hate in the party were smears designed to harm the Labour leader.

One senior communal figure said: “We may have won the battle but lost the war. I felt very uncomfortable listening to the debate.”

Another long-standing Jewish Labour activist said that despite the new policy, Tuesday had been “the worst day in my time in Labour”.

A senior JLM figure was adamant the outcome represented a “big result” and urged the community to consider the long-term benefits. The group had, it was claimed, “turned” Mr Corbyn to its view, securing his support and that of the influential hard-left Momentum group which is loyal to him.

The Board of Deputies welcomed the new rule, with chief executive Gillian Merron saying it was “a step in the right direction”.

However she later criticised Mr Corbyn’s speech to the conference as “a missed opportunity to address specifically the issue of antisemitism”.

At various meetings, party supporters questioned the Holocaust, compared Israel to the Nazis and called for Jewish groups to be expelled from Labour, prompting the Equality and Human Rights Commission to say that Labour “must do more to establish that it is not a racist party”.

Tuesday’s debate on the conference floor ahead of the vote on the new rule was marred by angry scenes. Naomi Wimborne-Idrissi, of the Jewish Voices for Labour group, warned that those seeking changes should “be careful”. She also claimed Jews who promoted the new rule had been “running” to brief right-wing newspapers including the Mail and the Telegraph.

Leah Lavane, a delegate from Hastings, received a standing ovation after she said it was not antisemitic to criticise Israel’s “despicable behaviour”.

In a passionate speech, Mike Katz, JLM’s vice-chair, said the party should ensure any members engaging in any form of hate should be “kicked out on their ear”.

Izzy Lenga, a National Union of Students vice-chair, tweeted after the debate that she felt more unsafe and uncomfortable on the conference floor than at student events.

Miko Peled, an Israel-born anti-Zionist activist, told a fringe event there should be free speech on every issue, including the Shoah. The same session saw Israel compared to the Nazis. He said: “This is about free speech, the freedom to criticise and to discuss every issue, whether it’s the Holocaust: yes or no, Palestine, the liberation, the whole spectrum. There should be no limits on the discussion.”

The event drew a furious response, with Labour Friends of Israel director Jennifer Gerber calling Mr Peled’s comments “beyond disgraceful”. Tom Watson, the party’s deputy leader, said there would be an investigation into the activist’s appearance.

A series of Mr Corbyn’s allies took to the airwaves, further worsening the atmosphere. When Ken Loach, the film-maker and Israel critic, was asked by the BBC about Mr Peled’s remarks on the Holocaust, he said: “History is there for us all to discuss.”

In a radio interview on Tuesday, Ken Livingstone, the former Mayor of London who is suspended from the party for remarks about Hitler and Zionism, said there had been a “distortion of the scale” of antisemitism in Labour. “Some people have made offensive comments, it doesn’t mean they’re inherently antisemitic and hate Jews,” he said.

Len McCluskey, the leader of the Unite union, attended an event on Monday organised by the Jewish Voice for Labour group which opposed the rule change. He later told the BBC he believed the antisemitism row of the past two years was “mood music that was created by people who were trying to undermine Corbyn”.

John Cryer, chair of the Parliamentary Labour Party, told a fringe meeting that he had seen “some of the tweets from paid-up Labour Party members and I am not kidding you, it makes your hair stand up”.

On Tuesday afternoon, Warren Morgan, the Labour leader of Brighton Council, wrote to the party’s general secretary warning that the authority might ban its own party from holding future conferences in the city if it did not clean up its act on Jew-hate.

Mr Corbyn did not attend the Labour Friends of Israel reception on Tuesday evening — the first such absence by a Labour leader in living memory.

Joan Ryan, the LFI chair, read a message from Mr Corbyn, but was disrupted by hecklers who shouted “where is he, why’s he not here?”.

Emily Thornberry, the Shadow Foreign Secretary, who attended instead, said Mr Corbyn was busy preparing for his “big speech” to the conference on Wednesday. As she spoke, Mr Corbyn was at a party being held by the Mirror newspaper. He later tweeted pictures of himself at three receptions run by trade unions.

Additional reporting byDaniel Sugarman and Lee Harpin