Eight people told Panorama they were undermined in their attempts to tackle alleged anti-Semitism in the party.
Former officials alleged that Labour’s director of communications, Seumas Milne, and its general secretary, Jennie Formby, interfered with investigations.
Four of those who spoke out, including former Labour general secretary Iain McNicol, broke non-disclosure agreements to do so.
Gideon Falter, chief executive of Campaign Against Antisemitism, said the show was “heartbreaking”.
He said: “Former Labour officials have been compelled by their conscience to speak out, revealing the scale of the duplicity behind Labour’s failure to address the party’s anti-Semitism crisis,.
“Whilst claiming to act against Jew hatred, Jeremy Corbyn’s agents and allies have carefully protected anti-Semites.
“It was heartbreaking to watch the testimony of honourable lifelong Labour officials contemplating suicide and suffering breakdowns because of the actions of Mr Corbyn and his team,” Mr Falter said.
“The charade of Jeremy Corbyn as an anti-racist activist has been blown apart. Mr Corbyn’s support for anti-Semites and his team’s protection of anti-Semites demonstrate that Mr Corbyn himself is an anti-Semite who is unfit to hold any public office.”
Tom Watson, Labour party’s deputy leader, said he was "shocked" and "angry after seeing the Panorama programme on Wednesday evening.
He added: "If I'm being honest, I feel deeply ashamed that we not acted quickly enough and it took their courage to speak out for it to be hopefully a watershed moment for our party."
Nick Lowles, chief executive of Hope Not hate, said the Panorama programme “was depressing and gut-wrenching”.
“It showed interference in what is supposed to be an independent process. It showed the downplaying of serious allegations. It showed an appalling lack of understanding of the hurt, and fear, felt by Jewish party members and the wider Jewish community,” he said.
Meanwhile, Sam Matthews, Labour’s former head of complaints, said he had been pushed to the brink of suicide by the issues in the party.
“After Jeremy became leader, he opened the floodgates and allowed people to join the Labour Party who never would have been allowed anywhere near it in the past,” he told The Jewish Chronicle.
“Whether he himself is an anti-Semite or not is an irrelevance. He is the biggest friend anti-Semites have had since the Second World War.”
Responding to the programme, a Labour spokesman said the party rejected any claim it is anti-Semitic and said it complained in advance to the BBC “over the way the programme was put together and its choice of a presenter who has expressed overt personal and political hostility to Jeremy Corbyn’s politics”.
“We stand in solidarity with Jewish people, and we’re taking decisive action to root out anti-Semitism from our movement and society.
“The Panorama programme was not a fair or balanced investigation. It was a seriously inaccurate, politically one-sided polemic, which breached basic journalistic standards, invented quotes and edited emails to change their meaning. It was an overtly biased intervention by the BBC in party political controversy,” the spokesman said.
“Despite claims made in the programme, Labour is taking decisive action against anti-Semitism. Since Jennie Formby became general secretary the rate at which anti-Semitism cases have been dealt with has increased more than four-fold.”