In life this man was the best-loved rabbi in Britain; his death is tearing the Jewish community apart

Rabbi Hugo Gryn was a survivor of Auschwitz, a broadcaster renowned for his wry and compassionate contributions to Radio 4's The Moral Maze and arguably Britain's best-loved Jewish leader.

So when he died last year, many in the Jewish reform movement which he led were furious that Dr Jonathan Sacks, the Chief Rabbi of Britain's largest group of orthodox Jews, failed to attend the funeral.

This Thursday the Chief Rabbi is expected to make partial redress when he speaks at an evening of tribute to Rabbi Gryn. But in doing so he has angered many orthodox rabbis who regard the late rabbi's brand of reform Judaism as heretical.

Five hundred people are expected at the ticket-only meeting at the Congress Hall, central London. Organised by the non-religious Board of Deputies of British Jews, the event is intended as a secular memorial.

The speakers will not only include the Chief Rabbi, but Hugo Gryn's son, David, together with the Bishop of Oxford, the Right Rev Richard Harries, and Rabbi Tony Bayfield, who heads the Reform Synagogues of Great Britain.

But, by attempting to bring people together from all sides, the memorial has become a focal point for a bitter debate on relations between the traditional orthodox and the liberal reform branches of the Jewish community. The position of the Chief Rabbi is at the heart of the matter.

In shunning the funeral, and then attending the tribute, the Chief Rabbi has been walking a tightrope that many on both sides believe is an unsustainable position. He is often regarded as the leader of British Jews and is, for example, the only Jewish leader at the annual remembrance ceremony at the Cenotaph. Yet his United Synagogue attracts only 40 per cent of the country's 290,000 or so Jews.

By sitting alongside reformers on Thursday - and justifying the decision by pointing to Rabbi Gryn's important inter-faith work - he will earn disapproval from his own side. Yet, if he fails to attend, the schism with reformers could be irreparable and his authority weakened.

Neville Nagler, the Board of Deputies' director-general, said that they hoped all sections of the community would come. "It's a meeting, not a religious service, and most people seem to find that quite acceptable," he said.

But not everyone. Rabbi Isaac Sufrin, an ultra-orthodox Lubavitch, said he would not "adjudicate" on what the Chief Rabbi did. However, Rabbi Gryn had been a reformer and "if Judaism means anything then nobody can change it ... I cannot give credibility to something which I believe goes against the truth. All that I believe was given to us through Moses from God on Mount Sinai."

However, David Walsh, vice-president of the Reform Synagogues of Great Britain, said he would be very pleased to see Rabbi Sacks at the meeting. Any divisions, he stressed, were within the orthodox community, not between the liberals and the traditionalists.

Yet he thought it very sad that the United Synagogue of the Chief Rabbi - which, he said, contained "very much middle-of-the road people" - felt unable to take part in any service alongside the reformed synagogues.

Rabbi David J Goldberg, chairman of the Rabbinic Conference of progressive rabbis, said it was "ridiculous" that the orthodox should claim not to "recognise" the reform wing when it had existed 200 years.

"This is where the fight is going to start - because we're not looking for acknowledgement. I find it unacceptable and bizarre that a person who has the allegiance of only 40 per cent of the people can be touted as a spokesman for Jewry."

However, he recognised that the Chief Rabbi was now in a difficult position.

"If I were a betting man," he said, "I would be inclined to put a small wager on a diplomatic illness between now and Thursday."