The Labour Party is to be investigated by the Equality and Human Rights Commission (EHRC) over whether it “unlawfully discriminated against, harassed or victimised people because they are Jewish”.

The statutory investigation follows a complaint from the Campaign Against Anti-Semitism, which said it took the “extraordinary step” as it felt Jeremy Corbyn had “repeatedly failed” to address Jew hatred in the party’s ranks.

The last party to be formally investigated by the equality body was the now-defunct BNP. 

The EHRC said it had contacted Labour after receiving a “number of complaints” about allegations of anti-Semitism and had “carefully considered” their response before opening the probe.

The investigation will now seek to determine whether “unlawful acts have been committed by the Party and/or its employees and/or its agents” and if the party has “responded to complaints of unlawful acts in a lawful, efficient and effective manner”.

Labour said it would co-operate with the EHRC but that it rejected the claim the party did not deal with complaints “fairly or robustly”. 

Jewish Labour MP Dame Margaret Hodge, who has spoken out about anti-Semitism in Labour, said it was a “truly disgraceful day” for her party.

She tweeted: “One of the most depressing in my 56 years as a member. Corbyn has completely failed from day one to take this issue seriously. The consequence is a full statutory investigation, he should hang his head in shame.” 

Gideon Falter, chief executive of Campaign Against Anti-Semitism, said: “There are only two reasons that the Commission has taken this extraordinary step. The first is that the Labour Party has repeatedly failed to address its own antisemitism problem.

“The second is that when the Commission approached the Labour leadership, they still failed to offer to action sufficient to reassure the Commission that the antisemitic discrimination and victimisation would stop.” 

Falter also hit out at Corbyn, Labour general secretary and the party’s ruling National Executive Committee for having “refused to listen to British Jews nor even to the MPs, MEPs, councillors and activists” who had raised the issue. 

He claimed Labour “was a great anti-racist Party has now become a home for hatred in British politics”. 

He added: “Over the course of his leadership we have seen enough to convince us that Jeremy Corbyn himself is an anti-Semite and unfit for any public office and though few have acted, most Labour MPs seem to agree with us.”

Change UK MP Luciana Berger, who blamed “institutional” anti-Semitism when she quit the Labour Party in February, tweeted: “For anyone who might look to play this down, the threshold to initiate this process is extremely high. That the Labour Party has even met the evidenciary threshold is damning.

“It should never have got to this – particularly for a political party which is supposed to pride itself on the values of equality and antiracism.”

Deputy Labour leader Tom Watson said: “I have been warning both privately and publicly that we risked a vortex of shame if we didn’t do everything in our power to root out anti-Semitism in our ranks.

“The decision of the Equality and Human Rights Commission to launch a statutory investigation into Labour shows they have reasonable suspicion that the party has unlawfully discriminated against, harassed or victimised people because they are Jewish.

“I feel utter shame that this investigation is necessary but I truly hope that it will provide the means to finally root out anti-Jewish racism from our party once and for all.”

Labour said Corbyn had repeatedly spoken out about anti-Semitism and had condemned those who employed it in his name. 

A Labour spokesman said Labour was “fully committed to the support, defence and celebration of the Jewish community” and “implacably opposed to anti-Semitism in any form”.

He added: “We support the efforts of the EHRC to draw attention to the obligations all political parties have under the Equality Act. But its ability to do so has been undermined by a 70% budget cut since 2010. Labour is the party of equality and in government we will strengthen the powers and functions of the commission.

“There has been a deeply worrying rise in anti-Semitism in the UK and across Europe. We are taking action to root it out of our party by strengthening our rules and procedures.

“But the issue can only be properly dealt with by all political parties working together to protect the interests of the Jewish community and to combat racism in politics, the media and in society more broadly. That includes the need for the Conservatives and other parties taking action to deal with racism in their own ranks.”