The former head of the London Beth Din Dayan Chanoch Ehrentreu has fired a shot across the bows of new Chief Rabbi Ephraim Mirvis by calling for a boycott of Limmud.

Rabbi Mirvis last month announced he would be the first serving chief rabbi to attend the cross-communal winter conference, which takes place in two months.

But in a notice signed by seven strictly Orthodox rabbis including Dayan Ehrentreu – which avoids mention of Rabbi Mirvis’s own decision – God-fearing Jews are advised “not to participate in any activitiy which is under the auspices of Limmud or similar organisations” .

It said that “participation in their conferences, events and educational endeavours blurs the distinction between authentic Judaism and pseudo-Judaism and would bring about tragic consequences for Anglo-Jewry” .

Rabbi Mirvis was "disappointed" by the notice and "disagrees with its contents," a spokesman said.

Only this week, United Synagogue president Stephen Pack predicted that more United Synagogue rabbis would follow Chief Rabbi Mirvis and attend the Limmud conference.

But the intervention of Dayan Ehrentreu, who retired as LBD head in 2006, may make some rabbis think twice about going.

The current Beth Din has voiced concern about Orthodox involvement in Limmud but recognised the chief rabbi’s prerogative to make his decision.