One of America’s most prominent pro-Israel advocates, Professor Alan Dershowitz, has written to President Shimon Peres to protest at the “religious tyranny” of Israel’s chief rabbinate.

He has intervened in a “who is a Jew” row that has flared up between the state’s rabbinical authorities and a leading American modern Orthodox rabbi, Avraham Weiss.

Rabbi Weiss was outraged when the state rabbinate recently refused to accept testimonials from him certifying the Jewish status of former congregants seeking to marry in Israel.

Prof Dershowitz warned of “a chasm between the Jews of the United States and the religious institutions in Israel”, saying he was “deeply saddened” at the shaming of his friend, Rabbi Weiss.

He wrote: “I am forced to see yet again how basic rights, such as the right to marriage, the right to self-definition and the right of religion, are trampled by none other than the Israeli democracy we value so.”

He called on Israel’s leaders to “understand that there is a serious problem which demands attention…” and that they must not bend to “baseless religious tyranny”.

In recent years, the chief rabbinate has tried to maintain a tighter grip on which rabbis are allowed oversee conversions and marriages.

Lawyers representing Rabbi Weiss said that his testimonials had been accepted by the chief rabbinate in previous years.

Rabbi Weiss, the senior minister of Riverdale Hebrew Institute, New York, is one of the leading lights of the “Open Orthodoxy” movement, which has been at the forefront of advancing the religious role of Jewish women.

Rabbi Weiss said that “once I heard from the inside that I am officially blacklisted, I felt it was important to go public. It’s a much larger issue. I am not the only one on the list.”