An internationally renowned Roman Catholic theologian called today for sweeping changes in the structure of the church to stem what he termed "the silent exodus from the church" of large numbers of priests as well as lay people.

The Rev. Dr. Hans Kung of the University of Tuebingen in Germany told an international conference on theology here that "the past 15 years have shown that the Catholic Church is unable to come to grips, within her present organizational structures, not only with the diverse needs of the church on the local, regional and universal levels."

The Swiss-born theologian, who was an official adviser at the Second Vatican Council, presented a list of changes he said are necessary to make the church "more flexible" and to "better fit it to respond" to the demands of contemporary life. These included:

"The consistent, uniform enforcement of a retirement age for Pope and bishops." Pope Paul VI, now nearing 80, has asked most bishops to retire at 75 but has said he himself will not retire.

Election of all "important decision making officials" of the church by electoral colleges of men and women "truly representative" of the units involved.

Periodic election and re-election of bishops, who now are named by the Vatican.

Moderation of the power of the Pope through a "representative synod of bishops" capable of making decisions "in concert with the Pope and (capable) of exercising a fraternal control of the exercise of papal power."

He also called for abolition of compulsory celibacy for priests, and for "equal rights for women in church life and office" including priestly ordination.

Kung, who has been involved in a running controversy with the Vatican over his views on papal infallibility, addressed a conference of more than 70 top-level Catholic theologians and social scientists gathered at the University of Notre Dame to explore the need for a Third Vatican Council.

The church is still caught in the turmoil that followed the sweeping reforms of Vatican II, which began 15 years ago. Most of the leaders assembled here believe they were not sweeping enough.

Kung said the reforms he advocates are necessary not only for the Catholic Church but also as a prerequisite for union, with other Christian churches which church leaders have long envisioned.

"The Catholic Church can only hope for a union when it is prepared to divest itself of certain historical prerogatives which today are generally acknowledged to constitute an insuperable obstacle to ecumenical progress," he said.