Labour admitted a previously barred activist who refers to his critics as "Zio idiots" and "Zionist scum", and claimed that Jews supported the Nuremberg laws, it has emerged.

Tony Greenstein, a prominent campaigner from Brighton, was barred from entry to the Party last summer when vetting of new applicant was stepped up during the leadership contest to prevent a surge of "entryism" from groups who did not share the "aims and values" of Labour.

However, following Jeremy Corbyn's election as leader, Mr Greenstein slipped back into the party unnoticed.

Evidence compiled by Labour's compliance unit when Mr Greenstein attempted to join the party last summer, seen by The Telegraph, included his claims in online forums Margaret Thatcher was an "obviously legitimate" target for the IRA and that "Zionists collaborated with the Nazis".

John Mann MP, chair of the All Party Parliamentary Committee into Anti-Semitism said that it was "hugely inappropriate" for Mr Greenstein to have been admitted to the Party.