Authorities say an Iranian-American journalist who worked for a U.S.-funded broadcaster is believed to have been detained by Iran for months, according to a report.

State Department officials acknowledged to the Associated Press that Reza Valizadeh has been imprisoned by the Iranian regime. Valizadeh worked for Radio Farda, the Iranian branch of Radio Free Europe/Radio Liberty, which provides “factual, objective and professional journalism” to its audience, broadcasting in Farsi from the Czech Republic. Iran’s theocracy views Radio Farda as a hostile outlet. 

Valizadeh’s detainment comes as Iran celebrates the 45th anniversary of the American Embassy takeover and hostage crisis on Sunday. Supreme Leader Ayatollah Ali Khamenei has also been threatening both the U.S. and Israel with a “crushing response” after U.S Defense Secretary Lloyd Austin ordered additional B-52 bombers and Navy warships to the Middle East amid rising tensions. 

Valizadeh in February had posted on X that members of his family had been detained in Iran and pressured to convince him to return to the country. 

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Holding a poster of the Iranian Supreme Leader Ayatollah Ali Khamenei, students attend an annual rally in front of the former U.S. Embassy in Tehran, Iran, Sunday, Nov. 3, 2024, marking the 45th anniversary of Iranian students’ takeover of the embassy, starting a hostage crisis. (AP Photo/Vahid Salemi)

In August, Valizadeh reportedly posted two messages that suggested he had indeed returned to Iran without guarantees for his safety. 

“I arrived in Tehran on March 6, 2024. Before that, I had unfinished negotiations with the (Revolutionary Guard’s) intelligence department,” one message read in part, according to the AP. “Eventually, I came back to my country after 13 years without any security guarantee, even a verbal one.”

Valizadeh included a cryptic message with the name of a man he claimed belonged to Iran’s Intelligence Ministry. The AP could not verify if the person worked for the ministry. 

The Human Rights Activists News Agency, which monitors cases in Iran, reported earlier this month that Valizadeh had been arrested and transferred to Evin prison. The report said he had been denied legal representation and that the charges against him remain undisclosed. 

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A schoolgirl holds an effigy of the Uncle Sam as another one holds a poster of the Iranian Supreme Leader, Ayatollah Ali Khamenei, in an annual rally in front of the former U.S. Embassy in Tehran, Iran, Sunday, Nov. 3, 2024.  (AP Photo/Vahid Salemi)

The State Department told the AP that it was “aware of reports that this dual U.S.-Iranian citizen has been arrested in Iran,” when asked about rumors that Valizadeh had been detained. 

“We are working with our Swiss partners who serve as the protecting power for the United States in Iran to gather more information about this case,” the State Department said. “Iran routinely imprisons U.S. citizens and other countries’ citizens unjustly for political purposes. This practice is cruel and contrary to international law.”

Iranian officials have not acknowledged Valizadeh’s detention. 

Since the 1979 U.S. Embassy crisis, which saw dozens of hostages released after 444 days in captivity, Iran has used prisoners with Western ties as bargaining chips in negotiations with the world. In September 2023, five Americans detained for years in Iran were freed in exchange for five Iranians in U.S. custody and for $6 billion in frozen Iranian assets to be released by South Korea.

Valizadeh is the first American known to be detained by Iran in the time since.

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Iranian demonstrators burn a representation of the Israeli flag in an annual rally in front of the former U.S. Embassy in Tehran, Iran, Sunday, Nov. 3, 2024. (AP Photo/Vahid Salemi)

Iran commemorated the anniversary of the embassy takeover on Sunday with thousands of demonstrators chanting, “Death to America,” and, “Death to Israel,” outside the former U.S. Embassy. Some burned U.S. and Israeli flags, the AP reported.  

They also carried images of killed top figures of Iran-backed terrorist groups including Lebanese Hezbollah leader Hassan Nasrallah and Palestinian Hamas leader Yahya Sinwar. The crowd in the state-organized rallies chanted they were ready to defend the Palestinians.

Iranian demonstrators burn a representation of the U.S. flag in an annual rally in front of the former U.S. Embassy in Tehran, Iran, Sunday, Nov. 3, 2024. (AP Photo/Vahid Salemi)

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Gen. Hossein Salami, head of Iran’s Revolutionary Guard, spoke in Tehran and reiterated Khamenei’s pledge to respond to the U.S. military’s presence in the Middle East and intensified engagements between Israel and Hezbollah in Lebanon. 

“The resistance front and Iran will equip itself with whatever necessary to confront and defeat the enemy,” Salami said, per the AP. 

Fox News Digital’s Jasmine Baehr and Liz Friden, as well as the Associated Press contributed to this report.