A ruling by Shas spiritual leader Rabbi Ovadia Yosef that celebrations of the Lag Ba'omer holiday should be postponed by a day to prevent desecration of the Sabbath has caused an uproar in Haredi (ultra-Orthodox ) circles.

The eve of Lag Ba'omer is traditionally celebrated with bonfires. This year, it falls on Saturday night, and to avoid tempting people to begin their preparations before the Sabbath ends, Yosef ruled that it should be marked a day later.

Both Ashkenazi Chief Rabbi Yona Metzger and Sephardic Chief Rabbi Shlomo Amar issued similar rulings. But many other ultra-Orthodox rabbis object and are continuing to prepare for the main bonfire-lighting on Mount Meron Saturday night.

Among them is the head of the anti-Zionist Toldot Aharon sect, which rejects the authority of the chief rabbis - including Yosef, a former chief rabbi.

The Lag Ba'omer celebration on Mount Meron has become Israel's biggest annual event, with some 500,000 people attending. Thus if the Mount Meron ceremony goes ahead on Saturday night, many policemen will find themselves having to desecrate the Sabbath in order to help prepare and provide security.

A source in Yosef's household said it was this factor that led him to rule in favor of postponement.

To avoid the problem of Sabbath desecration by police, the head of the Boyan Hasidic sect, who traditionally lights the first fire at Mount Meron, said he would not begin until half past midnight.

Last week, senior religious Zionist rabbis asked Education Minister Gideon Sa'ar to move the Lag Ba'omer school vacation from Sunday, May 22 to Monday, May 23. But the math matriculation exam set for May 23 made that impossible.