LONDON — A British-Iranian academic was arrested at his home in Tehran over the weekend, roiling relations once again between Iran and Britain just as they appeared to be making progress on the release of an Iranian tanker seized in Gibraltar.
The academic, Kameel Ahmady, an acclaimed social anthropologist of Kurdish origin, was detained on Sunday after Iranian security forces raided his house and seized documents, including his birth certificate, his wife, Shafaq Rahmani, said in a text message.
“A security prosecutor in Evin has issued a one-month arrest warrant for Kameel. No information about Kameel’s arrest or charge has been provided,” Ms. Rahmani wrote in an Instagram post, referring to Evin Prison, where a British-Iranian woman, Nazanin Zaghari-Ratcliffe, has been jailed since 2016 on espionage charges.
Her case represented a low point for Boris Johnson, the British prime minister, who as foreign secretary in 2017 mistakenly told Parliament that Ms. Zaghari-Ratcliffe was in Iran “simply teaching people journalism.” His comments were later cited in an Iranian court hearing as proof that she had been engaged in “propaganda against the regime.”
The British Home Office did not immediately confirm or deny whether Mr. Ahmady had been taken into custody.
Tensions between London and Tehran escalated last month after Britain seized an Iranian oil tanker in Gibraltar, accusing it of violating sanctions on Syria. Two weeks later, Iran commandeered a British tanker in the Strait of Hormuz, claiming marine violations.
On Monday, an Iranian official said that Gibraltar officials were preparing to release the Iranian tanker, but the British authorities did not confirm the claim and have previously dismissed the idea of a tanker swap.
“We are not going to barter a ship that was detained legally with a ship that was detained illegally. That’s not the way that Iran will come in from the cold,” the foreign secretary, Dominic Raab, said in a statement this month. “I am afraid some kind of barter or haggle or linkage is not on the table.”
Mr. Ahmady received his British citizenship in 1994 and studied at several universities in London before moving to Iran, where he has lived for the past 14 years, the Kurdish Human Rights Network said.
In recent years, he has published sensitive research on female genital cutting in Iran and the Shiite practice of “temporary marriage,” in which males and females, often in their teens, enter into marriage for a fixed period.
In June, Fariba Adelkhah, a French-Iranian anthropologist, was also detained in Tehran and denied consular assistance. Her research focuses on social and political change in Iran since the 1979 Islamic Revolution.
Iran does not recognize dual nationality and has detained several dual and foreign nationals in recent years. Britain upgraded its travel advice to British-Iranian dual nationals in May, advising against all travel to Iran.
“Dual nationals face an intolerable risk of mistreatment if they visit Iran,” Jeremy Hunt, then Britain’s foreign secretary, said in a statement. “Despite the U.K. providing repeated opportunities to resolve this issue, the Iranian regime’s conduct has worsened.”