On May 6 1691, Rabbi Raphael Valls, leader of the Chuetas, descendants of forced converts to Christianity in Mallorca who practised their Judaism in secret, was burned at the stake.

It was one of a series of auto da fes that year which took the lives of more than 30 Chuetas, the Catalan for "pigs", as the crypto-Jews were locally known.

But yesterday evening an official commemoration of that terrible event was due to be held for the first time.

Led by President Fransisc Antich Oliver, regional head of the Balearic Islands, the historic ceremony was to take place at the baroque Consolat de la Mar, a government building. It was arranged after a meeting a few months ago with representatives of Shavei Israel, an Israel-based outreach group that works with "lost" Jewish tribes.

Its director, Michael Freund, who was flying out for the ceremony, said: "It is highly significant because I believe it marks the first time a regional government in Spain is commemorating publicly what was done to the Bnei Anusim [forced converts] in the region."

He was due to be accompanied by a Jerusalem-based rabbi who is a descendant of Rabbi Valls. Also on the guest list was Palma-born Rabbi Nissim Ben-Avraham, of Chueta ancestry himself who converted back to Judaism in Israel.

An estimated 15-20,000 descendants of the Chuetas live in Mallorca, as well as a small local Jewish community including British expats.