The rift between Jeremy Corbyn and senior Jewish leaders has deepened after they demanded he disown supporters who had "vilified" anti-Semitism protesters.
In a fresh letter to the Labour leader, the Board of Deputies and the Jewish Leadership Council (JLC) said it was a "disgrace" that people who joined a demonstration against anti-Semitism in the Labour Party had been subjected to "abuse and insults".
They said Labour members and Labour-supporting blogs driving the abuse were "largely doing so in your name", undermining his pledge to eliminate anti-Semitism in the party.
They made clear that they were not prepared to take up his offer to meet until he had addressed the issue.
Their intervention came after Labour MPs who took part in the protest outside the Houses of Parliament on Monday said they had been subjected to "a torrent of abuse and threats of de-selection".
London mayor Sadiq Khan became the latest senior Labour figure to call for action to stamp out anti-Semitism in the party, saying he was "appalled and heartbroken" Jewish friends felt they no longer belonged in the party.
The latest letter to Mr Corbyn was signed by the president of the Board of Deputies Jonathan Arkush and JLC chairman Jonathan Goldstein who earlier this week accused him of "again and again" siding with anti-Semites.
While they acknowledged his apology for the pain caused by anti-Semitism in the party, they said it was essential that any meeting between them led to "concrete practical outcomes".
In particular, they said he "urgently" needed to address the abuse heaped on those who sought to raise the issue of anti-Semitism in the party - including Labour MPs - making clear it was not simply a "smear" against the party or its current leadership .
"Nobody should be vilified for opposing anti-Semitism. Those Labour Party members and Labour-supporting blogs pushing the abuse are largely doing so in your name," they said.
"They need to hear you say, publicly and in your own voice, that we had every right to protest about anti-Semitism, and that Labour MPs had every right to support us; that our concerns about antisemitism are sincere and not a 'smear' as has been widely alleged (including on your own Facebook page); and that anyone directing abuse, intimidation or threats at those of us who oppose anti-Semitism is damaging your efforts to eliminate it and to start rebuilding trust."
They also called for the swift resolution of complaints of anti-Semitism within the party, following reports that it has a backlog of 74 outstanding cases, some dating back two years.
Earlier, in a joint letter to Mr Corbyn, Labour backbenchers Wes Streeting and John Mann said they and other MPs who had spoken out against anti-Semitism in the party, had received "a torrent of abuse and threats of de-selection".
Mr Khan told BBC Radio 4's The World At One: "I'm appalled and heartbroken that Londoners of Jewish faith don't feel the Labour Party's for them. I think the Labour Party needs to do much more."
In the Commons, Theresa May said there was no place for racial hatred of any kind.
The Prime Minister told MPs: "There should be a very clear message from all of us in this House that there is no place for racial hatred, for hate crime, in our society - this should not be part of our society.
"Whether it is Islamophobia or anti-Semitism, this is something we should all stand up against and do our best to eradicate from our society."