One of the members of the three-person panel which agreed to let Chris Williamson back into the party, has issued a warning and called for the decision to be reviewed.
The Derby North MP – a strong supporter of Mr Corbyn – was controversially readmitted to the party on Wednesday after being issued with a formal warning by a National Executive Committee (NEC) antisemitism panel.
The decision produced a furious backlash from the Jewish community, while more than 120 Labour MPs and peers led by deputy leader Tom Watson demanding Mr Corbyn step in to withdraw the Labour whip.
Leicester East MP Keith Vaz has written to general secretary Jennie Formby expressing concern that the leaking of its ruling on Mr Williamson to the media meant its decisions in other cases could be subject to legal challenge.
He said that to ensure the “complete integrity” of the process, either a new panel should be convened or all the cases it dealt with on Wednesday should be referred to the party’s disputes committee for reconsideration.
Mr Williamson was suspended in February after video footage showed him telling a meeting of the Momentum group that Labour’s reaction to anti-Semitism allegations had led to the party being “demonised”.
He was also filmed saying he had celebrated the resignation of MP Joan Ryan, who quit Labour in protest over the handling of anti-Semitism and bullying complaints.
Vaz was quoted in PoliticsHome as saying: “”In my view, having served on the NEC for 15 years I consider the decisions the panel made yesterday cannot stand.
“In order to ensure complete integrity of the process either a new panel should be convened or all the cases from yesterday should be referred to the Disputes Committee for reconsideration.”