A small, ultraorthodox religious party has set back plans to set Israeli clocks ahead.

Israel's Cabinet today sidestepped the question of implementing summer daylight-saving time, despite assertions by virtually every government sector that it would save money and increase efficiency. But a number of major public and private institutions announced that they would unilaterally introduce an unofficial summer time anyway, sending their employes to work an hour earlier while Israel's Supreme Court considers the question.

As the debate heated up at the political level, underscoring steadily growing polarization between secular and intensely observant Jews, a popular rebellion got under way against the Cabinet's postponement of a decision on summer time.

Communications Minister Amnon Rubenstein, urging the Cabinet to resist "ultraorthodox blackmail," said the vast Postal Service would move its work schedule up an hour, as did manufacturers' and contractors' associations. The teachers' union and the central committee of the huge national labor federation, the Histadrut, said they were coordinating a turnover to summer time, and most banks said they would bring their employes to work an hour earlier if they get approval from the central bank.

Energy Minister Moshe Shahal, who estimated that daylight-saving time would save the country about $6 million in fuel costs alone this summer, condemned an atmosphere that he said was "part of the medieval age."

"I think that we should be part of the western world," said Shahal.

However, the man standing in way of summer time, Interior Minister Yitzhak Peretz, succeeded in blocking any Cabinet discussion on the issue until next Sunday and vowed to continue his opposition to moving the clocks up one hour.

Peretz, whose Sephardic Torah Guardians Party holds four seats in Israel's 120-member Knesset (parliament), said that summer time would result in no appreciable savings, and would be offensive to observant Jews because it would result in violations of the Sabbath.

An even smaller political party, the three-seat leftist Citizens Rights Movement, organized a large demonstration in front of Peretz's Jerusalem home at 6 a.m. today in which protesters rang alarm clocks and cuckoo chimes and chanted for Peretz to "wake up."

Orthodox opposition to summer time, which has been adopted for each of the last two years, is largely based on fears that it shortens the time that Jews have in which to pray after sunrise and still be at work on time. Orthodox Jews also complain that it leads to violations of the end of the Sabbath, which normally ends by 7:30 p.m. Saturday.