TEHRAN, Iran -- A U.S. student from Princeton University was arrested in Iran and sentenced to 10 years in prison on charges he was spying for the United States, an Iranian judiciary official said Sunday.

In the same news briefing, the Iranian judiciary said President Hassan Rouhani's brother has been detained over allegations of financial misconduct, authorities said Sunday.

News of the detentions comes less than two months after relative moderate Rouhani beat a hard-line opponent to win re-election by running in large part on his record of pursuing greater engagement with the West. They were announced by the judiciary, a pillar of hard-liners' influence.

The Chinese-American dual national was identified as Xiyue Wang, a 37-year-old graduate student in history, by Mizan Online, a website affiliated with the judiciary.

Wang was not previously known to be among the handful of Americans detained in Iran.

"It was verified and determined that he was gathering [information] and was involved in infiltration," judiciary spokesman Gholamhosein Mohseni Ejehi said during a routine news briefing.

The Mizan article said Wang was born in Beijing and entered Iran as a researcher. It pointed to graduate studies he did at Princeton University in 2013 and 2014, and described him as a fluent speaker of Persian.

The article did not identify Wang by name but included photos of him, and included a quote from Wang in which he had praised the British Institute of Persian Studies for facilitating access to Iran's National Archives and other libraries. The quote was used as evidence of his spying activities, the article said.

[EMAIL UPDATES: Get free breaking news alerts, daily newsletters with top headlines delivered to your inbox]

Princeton University did not respond to a request for comment.

"I have been having trouble accessing Tehran's archives and libraries," Wang said in the 2015-16 annual report of the British Institute of Persian Studies, a nonprofit organization based in London.

"Mrs. Reyhanpour offered to help," he said of one of the institute's employees. "And within a few days, she put me in contact with senior scholars at the National Archive. ... Without Mrs. Reyhanpour's help it would be hard to imagine how long it would have taken for me to become acquainted with academic institutions in Iran."

Wang was arrested Aug. 8 and is accused of passing confidential information about Iran to the U.S. State Department, Princeton's Sharmin and Bijan Mossavar-Rahmani Center for Iran and Persian Gulf Studies, the Harvard Kennedy School and the British Institute of Persian Studies, according to Mizan. Mizan alleged that he recorded some 4,500 pages of digital documents.

The U.S. State Department was not immediately able to provide details on the case. It said its citizens' safety and security is a top priority.

The U.S. does not maintain formal diplomatic relations with Tehran and warns its citizens traveling there that they risk arrest or being barred from leaving Iran.

"The Iranian regime continues to detain U.S. citizens and other foreigners on fabricated national-security related changes," it said in a statement to The Associated Press. "We call for the immediate release of all U.S. citizens unjustly detained in Iran so they can return to their families."

Wang's reported conviction comes at a particularly tense time for U.S.-Iranian relations, which have rapidly deteriorated since President Donald Trump took office.

Under the previous administration, the United States and other world powers negotiated a deal with Iran to curb its nuclear program in exchange for sanctions relief.

But since then, the Trump administration has stepped up its anti-Iran rhetoric and placed U.S. participation in the nuclear deal under review. Today is the deadline for the White House to decide whether to issue a waiver on nuclear-related sanctions against Iran, a provision that is required periodically under the terms of the 2015 nuclear deal. The administration is expected to approve the waiver, despite an internal debate on how to respond to Iran's human-rights abuses and support for militant groups such as Hezbollah.

The arrest of the president's brother, meanwhile, stunned many in Iran.

Ejehi said the brother, Hossein Fereidoun, was taken into custody over allegations of financial impropriety and is eligible for bail, but has not paid it yet.

Fereidoun is a close confidant of the moderate president, a cleric who changed his surname to Rouhani, meaning "spiritual," after joining the seminary decades ago.

Fereidoun was part of the negotiating team that ultimately sealed Iran's landmark nuclear deal with world powers in 2015, winning the country relief from international sanctions in exchange for limits on its atomic energy program.

The deal was unpopular with Iranian hard-liners, whose influence runs deep within the judiciary. They saw the nuclear deal as giving too much away in exchange for too little.

Fereidoun has long been a target of hard-liners, who have accused him of misdeeds including money laundering and misappropriation of government funds.

The unproven allegations were a flash point during the May presidential election, with the president's hard-line challengers demanding that the judiciary investigate accusations against Fereidoun.

Wang is one of several Americans in Iranian custody.

Iranian-American art gallery manager Karan Vafadari was detained along with his Iranian wife last year. They have yet to be convicted of a crime.

Iranian-American businessman Siamak Namazi and his 81-year-old father, Baquer Namazi, are each serving 10-year sentences for "cooperating with the hostile American government."

Another Iranian-American, Robin Shahini, was released on bond last year after staging a weekslong hunger strike while serving an 18-year prison sentence for "collaboration with a hostile government."

Still missing is former FBI agent Robert Levinson, who vanished in Iran in 2007 while on an unauthorized CIA mission.

Also in an Iranian prison is Nizar Zakka, a U.S. permanent resident from Lebanon who advocates for Internet freedom. He lives in Washington, D.C., and has done work for the U.S. government. He was sentenced to 10 years behind bars last year after being accused of espionage.

Information for this article was contributed by Amir Vahdat, Adam Schreck and Matthew Lee of The Associated Press; by Erin Cunningham and Carol Morello of The Washington Post; and by Rick Gladstone, Thomas Erdbrink and Matthew Rosenberg of The New York Times.

A Section on 07/17/2017