An influential Orthodox rabbi in Gateshead has said Senior Sephardi Rabbi Joseph Dweck is “not fit to serve,” after his comments on homosexuality.

Rabbi Shraga Feivel Zimmerman, Rov of Gateshead, who is widely regarded as a power-broker in Orthodox circles, penned his withering critique of Dweck in a letter to colleagues in London this week.

In it, Zimmerman admonishes the American-born Sephardi head for comments in May, when he said that the LGBT revolution had been a “fantastic” development for humanity. He has since been defended by more than 1,400 supporters, while others – mainly in the United States – have derided him as a “heretic”.

But in a no-holds-barred letter written in Hebrew, Zimmerman this week said of Dweck: “It is clear that he is not equipped to rule on Halacha, due to his limited knowledge, weak reasoning skills and lack of training.”

Zimmerman continued: “It is clear from his lectures that he lacks many of the 48 requisite qualities needed to acquire Torah, such as awe, fear (of Heaven), modesty, purity, Rabbinic training and scholarly interactions with his colleagues. For the above reasons one cannot rely on his rulings and he is not fit to serve as a rabbi.”

Chief Rabbi Ephraim Mirvis has met Dweck and the Sephardi leadership team on several occasions since 8 May, when Dweck first made his comments. Mirvis is believed to have given his advice on it.