Under the left-wing leadership of Jeremy Corbyn, the UK's main opposition Labour Party broke equality law through its "inexcusable" handling of anti-Semitism complaints, a government watchdog said in a major report published Thursday.
Keir Starmer, who has headed the Labour party since April, said the day of the report's release marks a 'day of shame' for the UK Labour party.
"It's a day of shame for the Labour party. We have failed Jewish people, our members, our supporters and the British public," he added.
The report by the Equality and Human Rights Commission (EHRC) found damning instances where Corbyn's former leadership team underplayed, belittled or ignored complaints by Jewish members, and sometimes actively interfered to support favoured allies.
In one of his first acts on replacing Corbyn in April, new Labour leader Keir Starmer apologised to Britain's Jewish community and he has vowed to accept whatever findings emerged from the two-year investigation by the EHRC.
"Our investigation has highlighted multiple areas where (Labour's) approach and leadership to tackling anti-Semitism was insufficient," the commission's interim chair, Caroline Waters, said in presenting the 129-page report.
"This is inexcusable and appeared to be a result of a lack of willingness to tackle anti-Semitism rather than an inability to do so," she said.
The commission said that under Corbyn, Labour was guilty of three breaches of Britain's 2010 Equality Act for political interference in complaints, failure to provide adequate training to those handling anti-Semitism cases and harassment of complainants.
But it stopped short of instituting legal proceedings, instead ordering Labour to draft an action plan by 10 December to remedy its failures.
Starmer in his comments on Thursday said the party will implement the EHRC's recommendations "as soon as possible in the New Year".
In a joint statement, the Board of Deputies of British Jews and two other Jewish organisations said the report was a "damning verdict on what Labour did to Jews under Jeremy Corbyn and his allies".
"Now, the task of cleaning out the problem lies with the current leadership. We welcome the start that Keir Starmer has made, but the scale of the challenge that lies ahead should not be underestimated," they said.
Corbyn's socialist views attracted thousands of new members but his leadership team was accused of failing to act on repeated incidents of anti-Semitic behaviour. His team deny this.
He triggered a leadership election after Labour suffered a hammering in a general election last December, which returned the Conservatives to power under Prime Minister Boris Johnson.
A leaked internal report by the UK Labour Party in April revealed that "hyper-factional" staff members allegedly hampered efforts by former party leader Jeremy Corbyn to tackle anti-semitism allegations.
The 860-page report, which came to completion towards the end of Corbyn's leadership, was intended as an annexe to an inquiry into Labour's handling of anti-semitism complaints by the Equalities and Human Rights Commission (EHRC).
Recently-elected Labour leader Keir Starmer has pledged to tackle anti-Semitism within the party. In June, Starmer sacked a leading rival from his top team for sharing an "anti-Semitic conspiracy theory".
Rebecca Long-Bailey was asked to step down as shadow education secretary after endorsing an interview with an actress who claimed US police accused of killing George Floyd learned their tactics from Israeli secret services.
"The article Rebecca shared earlier today contained an anti-Semitic conspiracy theory," a spokesman for Starmer said.
"As leader of the Labour party, Keir has been clear that restoring trust with the Jewish community is a number one priority.
"Anti-Semitism takes many different forms and it is important that we all are vigilant against it."
Starmer was elected Labour leader in April to replace Jeremy Corbyn, whose tenure at the helm of the centre-left party was marked by bitter splits.
Long-Bailey, a loyal supporter of Corbyn, ran for the leadership against Starmer and after missing out, he brought her into his top team in a public display of unity.
Corbyn responded to the report by saying he strongly opposed anti-Semitism and will continue fight "all forms of racism".
"The EHRC's report shows that when I became Labour leader in 2015, the Party’s processes for handling complaints were not fit for purpose. Reform was then stalled by an obstructive party bureaucracy. But from 2018, Jennie Formby and a new NEC that supported my leadership made substantial improvements, making it much easier and swifter to remove antisemites. My team acted to speed up, not hinder the process," he said in a statement on Facebook.
"Anyone claiming there is no antisemitism in the Labour Party is wrong. Of course there is, as there is throughout society, and sometimes it is voiced by people who think of themselves as on the left.
"Jewish members of our party and the wider community were right to expect us to deal with it, and I regret that it took longer to deliver that change than it should."