John McDonnell is facing calls to sever ties with a Labour group criticised for supporting members accused over antisemitism claims.
The Labour Representation Committee (LRC) hosts articles defending expelled member Jackie Walker and suspended MP Chris Williamson.
Mr McDonnell serves as the organisation’s president, and was recently featured in a video encouraging people to join the “incredibly successful” organisation.
Board of Deputies of British Jews president Marie Van der Zyl told Mr McDonnell: "This organisation has repeatedly defended and campaigned for individuals who have a long history of denying the problem of anti-Semitism in the Labour Party.
"On the basis of this, we would ask that you stand down from your position as president of this organisation.
"You have made helpful statements on countering anti-Semitism within the Labour Party, and we would therefore hope that you match these words with actions."
Mr McDonnell recently appeared in a video encouraging people to join the LRC.
Ms Walker was expelled from Labour this week following a three-year suspension for allegedly linking Jews with the Atlantic slave trade in 2016.
There were further complaints after she spoke out against the IHRA definition of antisemitism at an event intended to educate Labour figures about the issue.
Mr Williamson is currently suspended from Labour pending an investigation after claiming the party had “given too much ground” over antisemitism accusations.
The LRC website features a number of articles defending both Ms Walker and Mr Williamson, including articles agreeing with Mr Williamson’s comments.
Other articles claim that accusations of antisemitism within the Labour Party are a “witch hunt” and a “coup” against Jeremy Corbyn.
A spokesman for Mr McDonnell said: "John has no day-to-day involvement in the operation of the LRC and is not responsible for its website or for posts on social media by its supporters."