Shadow Chancellor John McDonnell is president of a group campaigning on behalf of Ken Livingstone and a party activist expelled for verbally abusing MP Ruth Smeeth.

The group is the Labour Representation Committee, which has posted a lengthy statement on its website backing Mr Livingstone, describing him as the victim of a “witch hunt” over his comments about Hitler and Zionism.

The LRC claims the remarks Mr Livingstone eventually resigned from the party over were "not remotely antisemitic".

It has also created a page on its website promoting a national speaking tour by Marc Wadsworth, who was expelled from the party in April for his verbal attack on Ms Smeeth at the launch of the party’s report into antisemitism.

The LRC statement on the Livingstone affair ends: “We must defend those unjustly suspended and expelled from the Labour Party. We have to fight for a genuinely impartial disciplinary process and oppose the kangaroo courts we are lumbered with at present. The only way we will get the Corbyn-led Labour government we want is not by conciliating and capitulating but by defending what is right and remorselessly combating the lies and smears of our opponents."

The site additionally features an “open letter” from Stan Keable, a leader of a Labour Marxists group, opposing his suspension from his job with Hammersmith and Fulham Council after being filmed claiming Zionists “collaborated” with the Nazis.

Mr McDonnell’s presidency of the LRC appears at odds with his pledge to "call out" hard-left websites propagating antisemitism.

His spokesman told the Telegraph that he was "just an honorary president of the LRC and plays no role in the content or decision making process of the organisation".

The LRC has described Labour MPs John Mann and Wes Streeting as "political pygmies” for “accusing Ken of antisemitism".

Mr Mann, who chairs the all-party parliamentary group on antisemitism, said he would file a formal complaint with the party about the LRC over its "appalling racist language" in relation to pygmies.

“I have met Batwa [pygmy tribe] leaders, visited their villages and seen the appalling conditions they live in.

"Those using this racist insult should hang there heads in shame, and be expelled from the Labour Party."