Labour deputy leader Tom Watson has written to Labour’s  general secretary, Jennie Formby, to say he found it "truly shocking and distressing" to hear ex-employees tell a Panorama documentary about the toll that dealing with antisemitism by party members has head on their mental health.

The BBC documentary accused Jeremy Corbyn's closest aides if interfering in antisemitism cases, which the party denies.

Mr Watson called on Ms Formby to publish the party’s submission to the Equality and Human Rights Commission (EHRC), which is currently investigating Labour over allegations it is institutionally antisemitic.

He also raised serious concern over the programmes claim that Ms Formby had deleted emails relating to antisemitism cases, which Labour also denies.

Mr Watson said: "These young people, particularly the ex-staff who broke NDAs (non-disclosure agreements) to speak out, have been very brave to go before a camera and tell their stories.

"The way that they have been smeared, including by Labour spokespeople, is deplorable. Even if some in the party did not want to hear what they had to say, it is unacceptable to attempt to undermine their integrity and characters in this manner."

Panorama highlighted one disciplinary case where Ms Formby had sent an email to senior Labour figures in which she said: "I’ve permanently deleted all trace of the email. Too many eyes all on my Labour address. Please use my Unite address."

Labour hit back at the BBC documentary, saying the allegations came from former “disaffected” staff with a "political axe to grind".

Mr Watson raised additional concerns about the email Ms Formby sent about deleting “all trace of the email” because earlier this year she told him the suggestion “that I or any of our staff would consider destroying evidence, or that we are incapable of understanding the importance of co-operating appropriately with a public authority……is offensive and totally without any justification."

Ms Formby responded to Mr Watson’s latest letter by saying she was “very disappointed” he had criticised the party’s handling of antisemitism.

She also said he was abusing his position as deputy leader.

She said: “The party has at all levels consistently shown that it recognises the vital importance of combating antisemitism, yet you consistently abuse your considerable platform to denigrate any progress that has been made and any individual that is involved in that.

“Traducing my reputation and publicly attacking me when you know I am undergoing chemotherapy and am unable to respond in the media is another example of the inappropriate way in which you choose to discuss this issue.”

Other senior Labour officials attack Mr Watson over the move.

Shadow Chancellor John McDonnell tweeted it the letter was sent “when he knows she’s undergoing chemotherapy”.

He wrote: “I just don’t understand why the deputy leader of the Labour party uses the media to demand information from Labour’s general secretary @JennieGenSec, which has already been offered to him.”