A British-Iranian anthropologist who studies controversial topics such as child marriage and female genital mutilation (FGM) in the Islamic Republic has been detained in Iran on unknown charges.

Kameel Ahmady was detained Sunday in Tehran, according to the New York-based Center for Human Rights in Iran and his wife, Shafagh Rahmani. They said he was being held in Tehran’s Evin prison.

Ahmady, who has dual nationality, released an authoritative study on FGM in 2015 that found the practice is being carried out in at least four major provinces while officials are silent on the matter.

“FGM is practised in Iran in some cases to tame girls’ sex drive before marriage; it is made to preserve their chastity,” said Ahmady. “The attitude of officials and authorities is that FGM doesn’t exist in Iran. The Iranian public is also largely ignorant about the subject.”

Iranian state media did not acknowledge Ahmady’s detention. Iran’s mission to the United Nations and the British Foreign Office did not respond to requests for comment on Wednesday.

Evin prison in Tehran, where Kameel Ahmady is thought to be held by authorities in Iran. Photograph: Ulrich Baumgarten/U. Baumgarten via Getty Images

Ahmady’s arrest makes him the latest dual national to be detained. British-Iranian woman Nazanin Zaghari-Ratcliffe was arrested at Imam Khomeini airport in Tehran in April 2016 and accused of spying, an allegation she denies. The Iranian-British dual national remains in prison in the Iranian capital after being sentenced to five years in jail in September 2016.

Last month, she detailed to her husband, Richard, how she spent six days in effective solitary confinement in Imam Khomeini hospital. She described the six-day ordeal to her husband as “proper torture”. “They did all they could to me – handcuffs, ankle cuffs, in a private room 2m x 3m, with thick curtains, and the door closed all the time. I wasn’t allowed to leave the room, as I was chained to the bed.”

It comes amid heightened tensions between Iran and the west over its nuclear program. President Donald Trump unilaterally withdrew the US from the accord last year.

Associated Press contributed to this report