Labour’s governing body has unanimously backed measures to make it easier to punish anti-Semitism in the party.

In a move personally backed by leader Jeremy Corbyn and the Momentum activist group, the national executive committee adopted proposals from the Jewish Labour Movement which make racism and specifically anti-Semitism a specific disciplinary offence for the first time.

But the addition to party rules must still be debated by delegates at the party’s annual conference next week ahead of a crunch vote which senior Labour figures hope will start to repair relations with British Jews after a string of controversies engulfed the party over the last 18 months.

“We are heartened that the NEC has adopted our rule change proposals and will be taking them forward to Party Conference [in Brighton] next week,” said JLM chair Jeremy Newmark. “This is another step forward, however our campaign will not end until these proposals are adopted in full by Conference itself – this is not a given and will require the firm support of the leadership.”

If passed, JLM – which first brought forward proposals for a rule change exactly a year ago – said the constitutional amendments “will simply bring the Labour’s rules to the place that should have been expected from a political party rooted in values of equality and anti-racism”.

It added: “The proof of the pudding will be in the eating. That means that if passed at Conference the new rules will need to be firmly implemented to create a zero-tolerance environment for antisemitism and other forms of discrimination. The Party will then need to take steps to rebuild its relationship with the Jewish community.”

Baroness Shami Chakrabarti, who was accused of failing to get to the heart of left-wing anti-Semitism in her report on the issue, played a key role in ensuring the proposals received backing across all factions of the NEC. Following the meeting, Corbyn thanked the peer and JLM for their work in drafting the motion, adding: “Jeremy is delighted that the NEC backed plans to tackle discrimination in the party. As a party of equality, there can be no place in Labour for prejudice.”

The move, whose specific wording was still hotly debated until the meeting itself, would finally brings racism in line with expressing support for another political party as a specific disciplinary category. It says conduct involving “racism, antisemitism, Islamophobia or otherwise racist language, sentiments, stereotypes or actions, sexual harassment, bullying or any form of intimidation towards another person on the basis of a protected characteristic” should be considered prejudicial to the party. JLM fought off an attempt to make genuine and sincerely held views a mitigating circumstance.

Senior Reform Rabbi Laura Janner-Klausner said Corbyn’s support for the rule-change was “a great move forward,” after a year in which he was criticised for not doing enough to tackle anti-Semitism on the left of the party.

The development comes after relations between Labour and the community reached an all-time low following the suspension of several elected officials and members. The scandal first erupted with the resignation of the former head of the Oxford Union Labour Club, who claimed a high proportion of the OULC have some “kind of problem with Jews”.

The party leadership have stressed their zero tolerance approach to anti-Semitism but MPs and Jewish leaders have repeatedly accused the party has at times failed to turn rhetoric into action. Last year Corbyn criticised the radio comments of his ideological ally Ken Livingstone, who said Adolf Hitler supported Zionism “before he went mad.” The former mayor was suspended but a disciplinary panel failed to expel him despite finding against him.

Elsewhere in the meeting, the NEC’s 35 voting members agreed to lower the bar for entry to Labour leadership elections, giving a boost to the party’s left-wing, one week before the party conference in Brighton. The NEC also voted to increase its membership from 35 to 39, allocating four more seats to unions and local party representatives – another coup for Corbyn, whose allies now hold the balance of power in Labour.