TEHRAN — The founder of a mystical, New Age version of Shiite Islam was sentenced to death by an Iranian court after losing an appeal, his lawyer said on Monday.

However, the religious mystic, Mohammad Ali Taheri, who was convicted on charges of founding a cult, is entitled to another appeal, the lawyer, Mahmoud Alizadeh Tabatabaei, said. An earlier death sentence for blasphemy against the 61-year old Mr. Taheri was overturned in 2014 by an appeals court.

In recent weeks, dozens of Mr. Taheri’s followers have been arrested across the country, especially around the central Iranian city of Isfahan.

But opponents of the spiritual leader say his conviction has nothing to do with proselytizing for a cult, saying he has had “illegitimate” sexual relations with women.