Jeremy Corbyn has been accused of bringing “collective shame” on the Labour Party over his handling of the row over anti-Semitism.

Former front bencher Chris Leslie said he was “absolutely mortified” by how the leadership had approached the issue.

The party has refused to adopt the definition of anti-Semitism set out by the International Holocaust Remembrance Alliance (IHRA), despite demands from MPs for it to do so.

Dudley North MP Ian Austin, the son of adoptive Jewish parents, faces possible disciplinary action for clashing with party chairman Ian Lavery over the definition.

Austin has said it was  just a “heated discussion” and claims he “screamed abuse” were false.

Leslie told BBC Radio 4′s Westminster Hour that Austin had “right as a backbencher to put those points forcefully to the establishment of the party”.

“It’s to our collective shame that this is still dragging on month after month. It’s certainly not in my name and it’s clearly not in Ian Austin’s name either,” he said.

LGBT Labour has also decided to back the IHRA definition in the wake of the row and called on the party to follow.

It comes after Labour MP Dame Margaret Hodge was also threatened with disciplinary action after confronting Corbyn in person.

Marie van der Zyl, president of the Board of Deputies of British Jews, has warned Corbyn was “leading the Labour Party into a dark place of ugly conspiracy theories” which had become a “home for overt anti-Semites and anti-Semitism”.

A party spokesman insisted Corbyn, a veteran Palestinian rights activist, was a “militant opponent of anti-Semitism” and determined to tackle it.

In a column for The Guardian, Austin, who has represented his West Midlands seat since 2005, added that “a minority of people” under Corbyn’s leadership “go way beyond legitimate and passionately held views about the plight of the Palestinians and tip over into anti-Semitism”.

He added: “But for others it is much more fundamental, whether it is Ken Livingstone’s nonsense about Adolf Hitler, legitimising the myth that Jews were the chief financiers of the slave trade, or outrageous comparisons between the actions of Israel and the crimes of the Nazis.

“Jewish MPs – particularly women – have been subjected to the most horrendous abuse.”

Labour’s governing National Executive Committee (NEC) did not include within its new code of conduct the full definition of anti-Semitism – including illustrative examples – set out by the IHRA.

While the code explicitly endorses the IHRA’s working definition of anti-Semitism and list of behaviours likely to be regarded as anti-Semitic word-for-word from the international organisation’s own document, it omits four examples:

– Accusing Jewish people of being more loyal to Israel than their home country;

– Claiming that Israel’s existence as a state is a racist endeavour;

– Requiring higher standards of behaviour from Israel than other nations; and

– Comparing contemporary Israeli policies to those of the Nazis.

Labour insisted the examples are covered in the new code.

A Labour spokesman said Corbyn and the party were “fully committed to the support, defence and celebration of the Jewish community and its organisation”.

He added: “The NEC has concerns about one half of one of the IHRA’s 11 examples, which could be used to deny Palestinians, including Palestinian citizens of Israel and their supporters, their rights and freedoms to describe the discrimination and injustices they face in the language they deem appropriate.

“We understand the strong concerns raised in the Jewish community and are seeking to engage with communal organisations to build trust and confidence in our party.”