In the Times, Ephraim Mirvis said "a new poison - sanctioned from the very top - has taken root" in the party.

Labour's claim it had investigated all cases of anti-Semitism in its ranks was a "mendacious fiction", he added.

Jeremy Corbyn says Labour is tackling anti-Semitism by expelling members.

It comes as Labour launches a "race and faith manifesto", which aims to improve protections for all faiths and tackle prejudice.

'Gripped by anxiety'

In the article, the Orthodox Chief Rabbi of Great Britain and Northern Ireland - who is the spiritual leader of the United Synagogue, the largest umbrella group of Jewish communities in the country - says raising his concerns "ranks among the most painful moments I have experienced since taking office".

But he claims "the overwhelming majority of British Jews are gripped by anxiety" at the prospect of a Labour victory in 12 December's general election.

He writes: "The way in which the leadership of the Labour Party has dealt with anti-Jewish racism is incompatible with the British values of which we are so proud - of dignity and respect for all people.

"It has left many decent Labour members and parliamentarians, both Jewish and non-Jewish, ashamed of what has transpired."

He adds that it was "not my place to tell any person how they should vote" but he urged the public to "vote with their conscience".

The Chief Rabbi - who has been a persistent critic of Labour's response to anti-Semitism allegations - claims the response of Labour's leadership to threats against parliamentarians, members and staff has been "utterly inadequate" and says it "can no longer claim to be the party of equality and anti-racism".

This is a sweeping and unequivocal condemnation of Labour's leadership, its treatment of Jewish parliamentarians and its handling of allegations of anti-Semitism.

It's also highly unusual for such an intervention by the leader of a religious denomination during a general election campaign. The Chief Rabbi has pastoral oversight of half the population of those who identify as Jewish in the United Kingdom.

Last week, the Archbishops of Canterbury and York appealed to voters and politicians to "honour the truth" and "challenge falsehoods" but there was no specific criticism of individual candidates nor their party leaders.

But the Chief Rabbi's article asks if Jeremy Corbyn is fit for high office and calls on voters to consider what the result of this election "will say about the moral compass of this country?"

Last year, three Jewish newspapers, - The Jewish Chronicle, The Jewish News and The Jewish Telegraph - published exactly the same front cover on 25 July - arguing that a Labour government under the leadership of Jeremy Corbyn would prove "an existential threat" to British Jewry.

The Chief Rabbi, in this highly critical column, is saying much the same.

The Labour leader faced criticism from Jewish groups when he said in last week's general election ITV leader's debate that the party had "investigated every single case" raised by complainants.

The Chief Rabbi takes issue with Mr Corbyn's claim, citing figures from the Jewish Labour Movement of "at least 130 outstanding cases".

Labour said: "The 130 figure is inaccurate and it is categorically untrue to suggest there are thousands of outstanding cases.

"We are taking robust action to root out anti-Semitism in the party, with swift suspensions, processes for rapid expulsions and an education programme for members."

On the Chief Rabbi's other points, a spokesman said: "Jeremy Corbyn is a lifelong campaigner against anti-Semitism and has made absolutely clear it has no place in our party and society, and that no-one who engages in it does so in his name.

"A Labour government will guarantee the security of the Jewish community, defend and support the Jewish way of life, and combat rising anti-Semitism in our country and across Europe.

"Our race and faith manifesto, launched Tuesday, sets out our policies to achieve this."

He added: "Anti-Semitism complaints account for about 0.1% of the Labour Party membership, while polls show anti-Semitism is more prevalent among Conservative than Labour supporters."

Anti-Semitism online

Proposed measures in Labour's "race and faith manifesto" include:

-Changing the law to include attacks on places of worship as a specific aggravated offence

-Working with social media firms to combat the rise of anti-Semitism online

-An independent review into the threat of far-right extremism and how to tackle it

-Reviewing the national curriculum to ensure it teaches about racism, anti-Semitism, Islamophobia, xenophobia and black history, and to continue education about the Holocaust

-Ensuring coroners services meet the needs of faith communities, with "out of hours" services to ensure quick burials when required, allowing some Jewish and Muslim families to bury loved ones in accordance with their religious practice

-Speaking ahead of the policy launch, Mr Corbyn said: "In government, Labour will do everything necessary to guarantee the security of the Jewish community, defend the Jewish way of life and the right to live it freely, and to combat rising anti-Semitism in our country and across Europe.

"We will protect the rights of Jewish people to practice their religion and ensure public services meet the needs of Jewish people, from coroners services conducting quick burials to proper provision of religious and culturally sensitive social care and youth services."