An American-born journalist working for Iranian state television's English-language service was arrested during the weekend after flying to the U.S., the broadcaster reported Wednesday.
Press TV said Marzieh Hashemi, born Melanie Franklin of New Orleans, was "detained upon arrival" at St. Louis Lambert International Airport on Sunday and has been transferred by the FBI to a detention facility in Washington, D.C.
The FBI told Fox News it had no comment on the claims by the broadcaster. Several local jails around Washington that house federal inmates told the Associated Press they did not have her in custody.
Iran's state broadcaster held a news conference and launched a hashtag campaign for Hashemi, using the same techniques employed by families with loved ones held by the government in the Islamic Republic.
"We will not spare any legal action" to help her, said Paiman Jebeli, deputy chief of Iran's state IRIB broadcaster.
Press TV said Hashemi, who is a Muslim convert and worked at the state broadcaster service for 25 years, was arrested along with her son, Reza Hashemi.
The broadcaster reported that Hashemi told her daughter she was "handcuffed and shackled" in addition to having her hijab forcibly removed, and was photographed without her headscarf upon arrival at the prison.
The only food she has had over the past two days has been a “packet of crackers” because she was only offered pork as a meal, which is prohibited in Islam, Hashemi was quoted as saying by Press TV.
The accounts of her treatment could not be independently verified by Reuters and the Associated Press.
The reported detention comes as Iran faces increasing criticism of its own arrests of dual nationals and others with Western ties, previously used as bargaining chips in negotiations with world powers.
Last week, Iran confirmed it is holding U.S. Navy veteran Michael R. White at a prison in the country, making him the first American known to be detained under President Trump's administration.
There are four other known American citizens being held in Iran, including Iranian-American Siamak Namazi and his 82-year-old father Baquer, both serving 10-year sentences on espionage charges. Iranian-American art dealer Karan Vafadari and his Iranian wife, Afarin Neyssari, received 27-year and 16-year prison sentences, respectively.
Chinese-American graduate student Xiyue Wang was sentenced to 10 years in prison.
Also in an Iranian prison is Nizar Zakka, a U.S. permanent resident from Lebanon who advocated for Internet freedom and has done work for the U.S. government. He was sentenced to 10 years on espionage-related charges.
Former FBI agent Robert Levinson, who vanished in Iran in 2007 while on an unauthorized CIA mission, remains missing as well. Iran says Levinson is not in the country and that it has no further information about him, though his family holds Tehran responsible for his disappearance.
The Associated Press contributed to this report.