The United Synagogue of Conservative Judaism, once the largest denomination in America, has announced sweeping changes aimed at halting a precipitous decline in membership.

The number of families affiliated with Conservative Judaism has fallen by 14 per cent in 10 years, according to a strategic report issued recently by the USCJ.

"Among congregations of every size and in every region, there is growing ambivalence about their continued membership in USCJ," the report warned.

Conservative Judaism's decline began during the 1990s, when affiliation fell from 43 per cent of American Jewish families to 33 per cent.

During the past decade, Conservative synagogues have been under pressure from modern Orthodox and Reform shuls as well as independent minyans. The recession only made matters worse.

Dr Jack Finkelstein, co-chair of the commission which issued the report, said the USCJ and its congregations had to do more to justify their fees.

"Especially in this consumer society," said Dr Finkelstein, "everyone wants to know what is the value added."

The strategic plan calls on the USCJ to reduce the fees it charges member congregations and to raise more money from philanthropy.

The changes were inspired by withering criticisms levelled at the USCJ two years ago by some of its largest member congregations, which felt the central body was insular, out of touch and a waste of money.

Jonathan Sarna, American Jewish history professor at Brandeis University, said that the troubles facing Conservative Judaism are being felt across the religious spectrum.

Prof Sarna said many shuls, not just Conservative, have suffered drops of "more than 20 per cent" in membership and dues. Only last week a South Florida Chabad synagogue filed for bankruptcy.

He said: "I think that we are seeing a new era - a much more difficult era for religious institutions as a whole."