A Labour MP has accused Jeremy Corbyn of “supporting and defending” extremists and anti-Semites in an astonishing attack on the party leader.

Ian Austin lashed out at the leader of the Opposition after it was revealed he is facing possible disciplinary action for clashing with the party chairman over the ruling National Executive Committee’s failure to fully adopt a widely-backed definition of anti-Semitism.

Austin, MP for Dudley North and the son of adoptive Jewish parents who lost relatives in the Holocaust, said the row that has seen Labour castigated by a string of Jewish groups had left him “deeply ashamed” of the party.

He accused Corbyn of introducing to Labour a more “extreme” brand of politics, telling BBC Radio 4’s The World This Weekend: “Somebody with views and history like his isn’t really suited to the leadership of a mainstream political party.”

Asked whether he was speaking out just because he did not want Corbyn to lead the party, Austin said: “He was never my choice to lead the Labour party that’s true, but what do people think? That I’m so worried about his plans to nationalise the railways or something that I would invent all this stuff?

“It’s actually the other way around. It’s because he has spent his entire time in politics on the extreme fringes of the Labour Party, supporting and defending all sorts of extremists and in some cases frankly, anti-Semites.”

Labour’s governing body, the 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 International Holocaust Remembrance Alliance (IHRA).

Labour’s code explicitly endorses the IHRA’s working definition of anti-Semitism and includes a list of behaviours likely to be regarded as anti-Semitic copied word-for-word from the international organisation’s own document.

But it omits four examples from the IHRA list:

– 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 that while the examples are not reproduced word for word, they are covered in the new code.

Austin, who has represented the West Midlands seat since 2005, said allegations he had “screamed abuse” at chairman Ian Lavery, sparking the disciplinary proceedings, were false, but admitted there had been a “heated discussion”.

Austin said: “I said that I thought the NEC’s decision was a disgrace.

“Am I upset about anti-Semitism? Yes I am. I am upset about that and I’m upset as well about the leadership’s failure, I think refusal really, to deal with this properly.

“I grew up listening to my dad tell me how he’d escaped from the Holocaust and how his mum and sisters were murdered in Treblinka (concentration camp) and that led to me joining the Labour Party as a teenager determined to fight racism.”

Last week Jewish Labour MP Margaret Hodge called in lawyers after being told she faced disciplinary action for confronting Corbyn in person over the issue of the IHRA definition.

Many other leading Labour MPs, including shadow cabinet members, have called on the party to adopt the full definition.

The UK’s three leading Jewish newspapers also took the unprecedented step of publishing a joint front page message warning that a Corbyn-led government would pose an “existential threat to Jewish life in this country”.

Under the headline “United We Stand”, the Jewish Chronicle, Jewish Telegraph and Jewish News described Labour’s refusal to adopt in full the International Holocaust Remembrance Alliance’s (IHRA) definition of anti-Semitism as “sinister”.

Marie van der Zyl, president of the Board of Deputies of British Jews, said the last few days had been “utterly shameful for the party”.

“Jeremy Corbyn is leading the Labour Party into a dark place of ugly conspiracy theories and it has become a home for overt anti-Semites and anti-Semitism,” she said.

“In 2018, Labour is not only a party with extravagant levels of tolerance for anti-Semitism but one which deliberately obstructs measures to counter hatred and punishes those who speak out against it.”