Mr. Ahmady said that after his 2019 arrest he had been held in solitary confinement for three months at the Evin Prison, north of Tehran, and blindfolded during repeated interrogations. Confinement was so excruciating, he said, that he yearned for interrogations, as they provided the only form of human contact he received.
“You just become mentally disabled, insensitive to your environment,” Mr. Ahmady told the British broadcaster Channel 4.
Mr. Ahmady, who is of Kurdish ethnicity, was born in northwestern Iran and received British citizenship in the 1990s. He has published several reports and books on genital cutting and child marriage in Iran. In a report published in 2015, he wrote that genital cutting was “embedded in the social fabric of Iranian culture” in at least four provinces.
“I know for sure that my prison term is a tool for the Iranian security services and the justice ministry to intimidate and pressure the remaining few people who are working on social issues,” Mr. Ahmady said in the statement published on his website on Wednesday.
According to local reports in December, prosecutors in Tehran accused him of working in concert with the United States and others, charges he has denied.
More than a half-dozen foreign and dual nationals are held in Iranian prisons, including Ms. Zaghari-Ratcliffe; Fariba Adelkhah, a French-Iranian academic; Siamak Namazi, a businessman, and his father, Baquer Namazi, a former official with Unicef, both Iranian-American; Dr. Ahmad Reza Jalali, a Swedish-Iranian physician and researcher; Nahid Taghavi, a German-Iranian architect; and Morad Tahbaz, an Iranian-American environmentalist.
Kylie Moore-Gilbert, a British-Australian scholar who was detained in 2018 on charges of spying for Israel, was released in December in a prisoner swap with three Iranian men.
Farnaz Fassihi contributed reporting.