The Board of Deputies has threatened to withdraw its support for a Manchester Israel advocacy conference unless organisers assure it that both Orthodox and Progressive voices will be given a platform.

The vice-president of Manchester's Jewish Representative Council, Mike Samuels, has already expressed his anger at the suggestion there will be a "no-platform policy for Progressive Jews" at the Big Tent for Israel Conference, due to take place on November 27 in Greater Manchester.

Board president Vivian Wineman said: "It is now an established practice that events expressing support of Israel are inclusive of all elements of the community, regardless of level of religious practice or belief. The Board heartily endorses that practice, and we have urged the organisers of the Big Tent to make this an inclusive event, and have told them that if they do not, we will not support it."

Mr Samuels wrote in a JC blog post about the Big Tent that "members of Reform, Masorti and other non-Orthodox communities will be welcome to attend but they would neither be permitted to share a platform nor lead any break-out or focus groups."

"Therefore this is an Orthodox Zionist event which strikes at the heart of the Stanmore Accords [a declaration against communal in-fighting made by the heads of the Orthodox and Progressive movements in 1998] where non-contentious issues, such as Holocaust education and Israel, are respected by all parties."

The Big Tent event was originally intended as a follow-up to Bicom's We Believe in Israel conference in May, but disagreements over content meant Bicom pulled out of any involvement in the Manchester event.

Manchester Jewish Representative Council voted last month to support the Big Tent and president Lucille Cohen is involved in the organisation, with Rabbi Jonathan Guttentag of Whitefield Hebrew Congregation and former Rep Council president David Arnold.

At the Rep Council meeting, Mrs Cohen said the event was "Orthodox-run. If the conference is under Orthodox auspices it has the prerogative as to which rabbis to invite."

Rabbi Guttentag used his Rosh Hashanah address to call for £80,000 to fund the conference. The event is taking place at the same time as the Reform Movement's Northern Communities' Weekend conference.

Rabbi Guttentag would not comment on the content of the conference or the speakers. He said: "I am involved in talks with the Jewish Leadership Council on matters that cover these issues and will be discussing them with my colleagues after Yomtov."

Chief Rabbi Lord Sacks and the chief rabbis of Poland, Italy and South Africa are believed to have been invited, raising questions about whether the event will have an explicitly religious theme. No other details about speakers have so far been released.