It is expected that the Equality and Human Rights Commission (EHRC) will launch a formal inquiry into the Labour Party over its antisemitism crisis.

Sources have told the Mail that the EHRC has been handed “compelling” evidence over Labour’s failure to tackle Jew-hate among its members. 

The watchdog asked Labour to respond to concerns about the allegations in March. The party provided its response last month, but it has been claimed that the EHRC was “deeply unimpressed” by the submission, in which Labour reportedly ascribed the problem to a “small number of individuals”.

One close ally told the Mail: “This will be a real blow to Jeremy and it will go on for months and months. It’s the last thing we need.”

Sources also claimed that evidence submitted by the Jewish Labour Movement (JLM) via lawyers at Mishcon de Reya were seen by the EHRC as “compelling”.

In an EHRC investigation, Labour would likely be asked to implement an “action plan” to change the way it processes complaints.

The party said it had been co-operating with the EHRC, and added: “We completely reject any suggestion the party has acted unlawfully.”

A spokesman said: “Labour is fully committed to the support, defence and celebration of the Jewish community and its organisations. We are determined to tackle antisemitism and root it out of our party.”