Michael Foster, the Jewish Labour donor who launched a legal challenge against Jeremy Corbyn, has said he has been accused by supporters of the party leader of using false claims of antisemitism to smear left-wingers.

Mr Foster, whose family has donated over £400,000 to the party, described Mr Corbyn’s allies as resembling “stormtroopers” who threatened and intimidated opponents.

In an article in the Mail on Sunday, the retired businessman said he had been denounced for “plotting to falsely use the accusation of antisemitism” as part of a right-wing “conspiracy” to undermine Mr Corbyn.

He added: “The ancient racist rhetoric is that Jews don’t act alone, the malevolent Jew always conspires”.

Mr Foster, who lost eight members of his family in the Holocaust, made the comments

after losing his High Court battle to prevent Mr Corbyn running in the Labour leadership contest without first gaining the support of the party’s MPs.

The court had handed a victory to “Corbyn and his Sturm Abteilung (stormtroopers)", he said.

But he welcomed Friday’s Appeal Court decision to allow Labour’s National Executive Committee to block 130,000 new party members from voting in the leadership contest as a triumph for democracy.

Mr Foster, who ran as a Labour candidate in the 2015 general election, said Owen Smith, Mr Corbyn’s rival for the leadership, had a real chance of winning September’s vote. Should he do so, it would spell the end for the hard left “bullies”, he believed.