The number of Reform rabbis who publicly say they perform mixed marriages has increased from 78 in 1973 to 157, according to Rabbi Irwin H. Fishbein of Westfield.

He said more than 300 other rabbis said they perform mixed marriages but did not want to be publicly identified. He said his findings were gained from a mail survey of Reform rabbis last year.

Rabbi Fishbein's report showed that most of the 157 rabbis who publicly said they were willing to perform mixed marriages gave qualified answers. Abour 117 said they would require some commitment by both partners that they would raise their childdren as Jews or would take some form of Jewish study.

Only 16 said they would officiate at a marriage ceremony in a church; 47 said they would share a service with a priest or minister.

Mixed marriages have been opposed by most U.S. Jewish bodies. In 1973 the Cultural Conference of American Rabbis, the Reform rabbinical organization, declared its "opposition to participation by its members in any ceremony which solemnizes mixed marriages."

Despite the offcial opposition, some Reform rabbis express the view that such unions are increasing and the Jewish community should give all possible support to the couples, including a marriage ceremony.

"If a Jewish person asks me to be present at such an important moment in life, I am not going to say no," said Rabbi Fishbein, who heads a research and counseling center hare and maintains a referral list of rabbis willing to perform mixed marriages.